Your Cheating Heart



"''Your cheatin' heart will make you weep,

You'll cry and cry and try to sleep.

But sleep won't come the whole night through,

Your cheatin' heart will tell on you.''"

- Hank Williams, "Your Cheatin' Heart"

Two-timing, playing away from home, having a bit on the side, going behind your partner's back, adultery, infidelity... There are a lot of names for cheating on your partner, but most of them have the same outcome: a world of hurt.

Most of us recognize this type of plot: Bob is married to Alice. One day, Bob sees Dorothy at a club and is attracted to her. Perhaps things haven't been going so well with Alice for some time. Maybe they just had a major fight and Bob stormed off. Or maybe his marriage is perfectly healthy, and Bob has no other excuse than his own selfishness/egotism/libido. Whatever the reason, Bob flirts with Dorothy, which eventually leads to a romantic relationship and the various things that entails. But here's the thing: Bob doesn't tell Alice about it. He doesn't dump her, he doesn't tell her that he thinks the marriage is on the rocks, he doesn't even ask for "more space". He continues to play the part of her husband, and expects her to continue being his wife, hoping that Alice won't notice when he starts coming in late for dinner, or ask him about the mysterious expenditures on their joint account. Sometimes, just to really play Alice for a sucker, their marriage will seemingly start to improve-- he buys Alice gifts, pays attention to her and seems much happier, but all the while he's running off to see Dorothy. For extra scumbag points, he may be keeping Dorothy similarly in the dark about Alice.

Chances are he'll eventually get caught; if he didn't, the story wouldn't have the same dramatic impact. A lot of angst and tension will ensue instead.

Way back in the day, when marriage was considered permanent and divorce was a word whispered fearfully by gossiping old ladies, The Affair was a shocker of a storyline, and very often an automatic Moral Event Horizon for the cheating partner. However, it's worth noting that even further back in the day, the gods, goddesses and minor side characters of mythology listed "infidelity" under "Hobbies", didn't particularly care if their new "partner" was willing, and got away with it. Well, the gods and goddesses did for the most part. Not so the luckless mortals they seduced -- they got the nasty side of the wronged wife's/husband's temper when the affair was discovered.

Nowadays, affairs are almost mandatory in any Soap Opera, and turn up an awful lot in other types of story as well. We don't really expect a fictional husband and wife to stay faithful to each other for forty or so years. Supposedly, a solid marriage makes a boring story (though some would disagree). Often, a sequence of "get together -> one cheats -> they break up -> they make up -> the other one cheats", and so on) will be followed so often and so tiresomely that it becomes a Yo Yo Plot Point.

Interestingly, our attitudes as viewers have changed towards cheating as well. For a start, what we define as cheating has changed. Kissing someone who wasn't your partner/spouse used to qualify, but now many writers and viewers are unsympathetic to a husband or wife who freaks out over "just a kiss" when they find their significant other lip-locked with a stranger; most people maintain that "an affair" has to involve sex.

A few rules usually hold true in fiction though: Women who cheat are generally portrayed much more sympathetically than men. The (male) big boss of any given workplace is practically obliged to be two-timing his wife. The protagonist remains sympathetic if they cheat, and becomes an innocent, wronged victim if they are the one being cheated on. Bisexuals are shown as incapable of being faithful (though, it seems to be either that or merely informed sexuality), and men are more prone to having affairs than women.

Unfortunately, adultery is Truth in Television, as many broken hearts and broken families will testify.

See also Mistaken for Cheating, The Unfair Sex, The Mistress. This is generally the #7 scenario of Triang Relations.

Anime and Manga
"Maka: What excuse do men have for cheating?
 * In Victorian Romance Emma, William is technically guilty of this as well, despite being sympathetic. Told to give up on his love for Emma, he proposes (under duress, it has to be said) to a more "suitable" Proper Lady, Eleanor. On reuniting with Emma however, he continues their chaste love affair while he is still officially betrothed to Eleanor, until he finally breaks the engagement.
 * Cheating, or rather, paranoia about being cheated on, is a source of humour in Kyou Kara Maou -- Yuri's jealous male fiance, Wolfram, calls him "cheater" so often it's practically a nickname. In fact, Yuri only has to be nice to anyone, of either sex, to set Wolfram on a rampage. Whether Yuri is actually capable of cheating, however, depends on whether the viewer considers their accidental engagement valid or not.
 * One example comes in the Fruits Basket manga. A teenaged sleeps with her cousin  in an attempt to ensure that he won't abandon her, . When  finds out, he sleeps with her mother, partly to get back at  and partly for the family resemblance between mother and daughter. When she finds out, she flies into a jealous rage , not forgiving him for several years.
 * Blue Eyes.. The main character Tatsuya, gets into the pants of 7 girls by the end of volume 9 (the last one made recently) and it's implied he might get even MORE. And his main girlfriend is only aware of one of these girls. The other five? She doesn't suspect a thing and neither do they.
 * Happens several times in Pet Shop of Horrors and its sequel series. Generally, this is enough to get one ripped up or horribly poisoned or killed by something. One noteworthy example was when the sweet-looking wife of a gang boss hired a hot woman for some purpose for her husband. The implication was that the woman was an assassin and would kill a rival mafia leader.
 * School Days. Makoto sleeps with pretty much every female character except for his initial girlfriend. He cheats on said girlfriend with another girl, and cheats on her with two more girls.
 * In Soul Eater, Maka's father cheated on her mother, which made her completely paranoid of this and convinced that All Men Are Perverts. She frequently beat up on Soul for getting a nosebleed at the sight of Blair, and had a complete breakdown when he seemingly left her for Blair, culminating in this combination of Tear Jerker and Crowning Moment of Heartwarming:

Soul: How should I know? Cool men don't cheat."


 * She got better after she got used to Blair living with them.
 * In Oniisama e..., This was the cause of  's distrust towards men.
 * Discussed, but ultimately averted with.
 * Sakurai from After School Sex Slave Club who drugged her boyfriend and then proceeded to have sex over him with multiple boys.
 * Played for Laughs in Sailor Moon, where Minako was paralelly dating two men: the sensitive artist Takano and the Badass Biker Torashima.

Film

 * In Deconstructing Harry, this has been the protagonist's M.O. for all his life, to the point he's broken up several marriages; the very start shows him
 * In Fatal Attraction, the cheating husband is played as a victim when his mistress turns out to be a scary stalker who puts his daughter's pet rabbit in a pressure cooker. In one ending she, while we don't see what the wronged wife does to her cheating husband after the events of the movie. Given that the affair endangered her child (the mistress could very easily have gotten her hands on said child, and was crazy enough to pose a potential threat), the cross between Mama Bear and Woman Scorned would be the really scary part.
 * Mr. Destiny screws with this, when the main character (not the titular character) ends up in an alternate reality where he and his wife are married to different people.
 * Mary Jane Watson in the Spider-Man movies is usually cheating on someone. In the first film she cheats on Harry by kissing Spider-Man in the rain. In the second film she is engaged and cheats with Peter Parker. In the third film, she is indignant that Peter kisses another girl upside down because that's "their kiss," even though when she first did it, she was the one cheating.
 * The entire plot of the 2002 film Unfaithful is this trope.
 * The comedy of Unfaithfully Yours comes from how the main character deals with thinking his wife is cheating on him.
 * Michael Godwin in Swordspoint makes a habit of sleeping with married people (of both genders).
 * The House of Yes: A rather disturbing example happens in the climax.
 * In Love Actually, Alan Rickman's character appeared to be emotionally cheating on his wife with his secretary by buying her an expensive necklace while buying his wife a CD. However, the CD was what his wife wanted (proving that he did love his wife) and at the end of the movie, despite his wife finding out about the necklace and him admitting to getting it for his secretary, they're not together but have reconciled.
 * One of the major plotlines in Swing Shift is Kay's eventual affair with Lucky while her husband is away at war. Naturally it turns out badly, though Kay and her husband do reconcile later.
 * In Eve's Bayou, one of the main plot points is 9 year old Eve catching her father with another married woman. Turns out her father often has affairs with his patients.
 * Bumblebee actually plays the Trope Namer song to remind Sam of the trope in Transformers: Revenge of the Fallen.
 * It's worth noting that Sam is actively resisting the other girl, who's coming on very strong. Then again, she's a.
 * Happens all over the place in Forgetting Sarah Marshall. First we have the titular character cheating on her boyfriend Peter with the British Rock Star Aldous Snow (later, it's revealed that they've been sleeping together for a year before she told Peter. At dinner, Aldous starts talking and claims that he has a right to bed any woman he wants, which implies that he may have already done so while being with Sarah. Finally, after Aldous breaks up with Sarah, she tries to get back together with Peter, and they even start having sex, before Peter snaps back and leaves in mid-blowjob. Unfortunately for him, he then tries to explain himself to his new girlfriend Rachel, who promptly breaks up with him. Luckily, they get back together after a while.
 * Loverboy is about a college slacker (played by Patrick Dempsey) who, unexpectedly, finds himself in the escort business, sleeping with women (all order than him) whose husbands are ignoring them. Why? So he can pay for college and get back to his girlfriend. He sees nothing wrong with this up until the end, when she confronts him about it and is uncertain she wants to stay with him. Interestingly, she doesn't immediately shut him out and appears to understand that he meant well. Then there are his three primary clients, who are obviously cheating. Their husbands are implied (and one outright admits it) to also be cheaters. At the end, two of the couples get back together, seeming to forgive each other's "mistakes". One, though, decides that she's had quite enough of her husband who treats her "like a geisha" and leaves him to rot in jail.

Literature

 * The Chairman from Memoirs of a Geisha is already married when he gets together with Sayuri, but in this case a man being married and having a danna relationship with a geisha was not frowned upon and was indeed a sign of status during that period. It wasn't cheating as we think of it.
 * In Stardust, Victoria despite promising to marry Tristan when he returned with a star got engaged to another a man while he was away. Of course, when she set the Engagement Challenge she hadn't expected him to actually go into Faerie and bring back the star, and did offer to break off her engagement and keep up her end of the bargain.
 * The unnamed father in Chapter 36 of The Pale King has multiple affairs. He gets off on the idea of women needing him.
 * Sisterhood series by Fern Michaels: A number of villains have engaged in this trope. Senator Webster in Payback. Rosemary Hershey in Sweet Revenge, who is female, and her cheating is in no way presented in a sympathetic light. Roland Sullivan in Lethal Justice. Mitch Riley in Hide And Seek. Baron Bell in Deadly Deals. A couple of them receive a divorce as one of the consequences. Interestingly, the trope gets deconstructed in Payback. It's like this...Senator Webster cheated on his wife Julia Webster with multiple women. She had him write down a list of the women he had affairs with. One of them is married, and Julia points out that her husband would have performed mayhem on the Senator if he had known. The real clincher is that the Senator got infected with AIDS from one of the women, and he ended up giving it to Julia! He didn't know he was infected, but still.... Of course, she did reveal the truth to him that they both have AIDS, and he naturally could not believe that powerful he had been infected by such a thing. It goes to show that recklessly sleeping around is not bliss, and that it is in fact dangerous!
 * It's hard to find an Agatha Christie novel that doesn't contain cheating (or pretense thereof).
 * In Death on the Nile, it's
 * Don't even get me started on Five Little Pigs.
 * In Murder at the Vicarage, Anne Protheroe and Lawrence Redding are having an affair. (Not really a spoiler. It's revealed comparatively early in the book.)
 * In The Mysterious Affair at Styles,
 * In Sad Cypress, the protagonist, Elinor Carlisle, is charged with murdering the hypotenuse when her fiance falls in love with a girl who dies of morphine poisoning.

Live Action TV
"Kelso: Alright, look. Jackie, here's the deal, you cheated on me.
 * Par for the course in Scrubs: Jordan's promiscuity is legendary before she finally settles down, Dr. Kelso has been having at least one affair at a time throughout his marriage, and J.D. and Turk are both tempted to cheat at various points in the story. At one point J.D. made the questionable decision to tell his girlfriend about how he could have cheated on her with the woman he'd lied to her about what he was doing that night to meet, but hadn't.
 * Most of the cast of any given Soap Opera will have at least one affair to their name -- Coronation Street and Eastenders are particularly fond of this as a plot.
 * Pick any crime show or detective drama. About half to two-thirds of the time, the murder had to do with someone having an affair. (The rest of the time, it's usually about money.)
 * Used regularly on the comedy Last of the Summer Wine, principally (but not exclusively) with Howard and Marina. Here, the justification for using marital infidelity as comedy is that the characters are generally unattractive and lack the courage to take their affair to a very intimate level. And the fact that for all the absurd lengths they go to in order to cover it up, the wife knows full well what's going on and is not impressed.
 * Too many to count in Skins - the show has been criticsed in some quarters for relying on cheating as the primary generator of conflict.
 * Series 1. Tony cheated on Michelle with many women and one man.
 * Okay, running count. Series 2:
 * Sid cheated on Cassie with Michelle.
 * Michelle on Tony with Sid. Debatable as they split up in series 1.
 * Chris on Jal with Angie.
 * Series 3:
 * Pandora on Thomas with Cook.
 * Freddie on Katie with Effy.
 * Emily on Naomi with JJ. (Dubious, because they weren't entirely sure if they were actually dating or not, but Naomi certainly plays it that way.)
 * Which turns Naomi into a hypocrite, since her and Emily's relationship at that point consisted of Naomi coming up with excuses that made it possible for her to consider herself straight in-between make-out sessions and her freaking out and leaving Emily in the middle of the night after their first time together.
 * Series 4:
 * Emily on Naomi with that random at the barbeque.
 * Emily on Naomi with Mandy (although it took a while for Naomi to get it).
 * That's eight separate instances of cheating in barely 30 episodes.
 * In Noah's Arc,.
 * has an affair with in Torchwood.
 * She feels really guilty about it, though, and tells Rhys... after spiking his drink with Retcon. While she wants to hear him forgive her, she doesn't really want this to end their relationship. She ends up breaking off the affair and marrying Rhys.
 * Much of the drama in Flash Forward is derived from Mark's wife Olivia having a vision of herself with another man in six months' time.
 * A standard plot-line in Gossip Girl, with literally too many instances to list and many of them too complicated to explain.
 * Prime example is Dan Humphrey. He's cheated on three out of four girlfriends.
 * It would be easier to list the characters who have been faithful on The Secret Life of the American Teenager than list the many instances of cheating.
 * Taub of House is a big offender, despite his recent efforts to stay faithful to his wife.
 * The early seasons of MASH take a pretty casual attitude towards adultery. Henry Blake, Trapper John McIntyre, and Frank Burns are all married men who are having affairs while serving in Korea.
 * Conversely, in a season 6 episode B.J. Hunnicutt cheats on his wife and feels terrible as a result.
 * The Tudors has a lot of this. Henry cheats on his first three wives. Katherine of Aragon takes it stoically, Anne Boleyn blows up over it, and Jane Seymour actually doesn't seem that bothered - she is perhaps remembering that Anne Boleyn got her head cut off and is therefore being cautious. Plus, is was perfectly normal and socially acceptable for a man in Henry's position to have multiple mistresses, so whether it would actually be considered as "cheating" by the standards of the time is debateable. Needless to say, the same rule did not apply for married women. Wife no. 5, Katherine Howard cheats on Henry with Thomas Culpepper, and is executed for it. Part of what ruins the Charles Brandon/Princess Margaret marriage is that Charles can't be faithful. Both of the gay couples on the show involve married men, so they're cheating on their wives. Technically Ursula Misseldon was cheating on her fiance with Francis Bryan and Henry. Anne Stanhope cheats on Edward Seymour twice, first with Francis Bryan and then with his own brother, Thomas (though we never know for sure if Edward knows about the second). She also flirts with the Earl of Surrey, but Edward seems to have been encouraging that one... It's also inverted, since Anne Boleyn gets executed for adultery when she didn't cheat on Henry.
 * What's really wild is that 90% of this is Truth in Television in fact if anything there was more screwing around in Henry's court than the show actually portrays.
 * In The Mentalist, Bosco's utter devotion to Lisbon is played completely sympathetically, even though he is married. It may help that Lisbon is stoutly convinced that Bosco doesn't love her back, and actually cites his wife as a reason. Turns out she was wrong.
 * Jimmy Mcnulty is the personification of this trope
 * Kima gets there too
 * Danny Messer on CSI: NY during the Will They or Won't They? period of his courting Lindsay. A boy in Danny's care was shot, and mourning and comfortsex with the kid's mom ensued.
 * Subverted on CSI. It did look like Doc Robbins' wife was cheating, but it turned out to be a set-up involving a disgruntled, arguably Ax Crazy guy looking to off a genealogist who pulled up some dirty family secrets on him and Mrs. Robbins just happened to be said genealogist's next client.
 * Played straight in Brass's backstory. It was a double cheat, since they were both cheating on each other. Ellie resulted from the wife's affair.
 * Tony Soprano is another walking adulterer. The wife kind of tolerates it until he cheats on her with a one-legged woman, a ultimate humiliation.
 * Don Draper is the quintessential cheater.
 * In Season Three of Buffy the Vampire Slayer, Willow and Xander cheat with each other on Oz and Cordelia, respectively. They don't have sex, but these are high school relationships, so making out is as far as anyone is going. They are eventually discovered. Cordelia breaks up with Xander, and temporarily leaves the Scooby Gang. Oz eventually forgives Willow. Both Willow and Xander remained sympathetic, mostly because they were very distraught over their powerful attraction to one another.
 * Oz cheated on Willow in Season Four with fellow werewolf Veruca. This time, sex was involved, but because Oz was a werewolf when the cheating took place, and not in control of his actions he was plainly and visibly struggling with mating urges the wolf inside him was feeling toward the wolf in Veruca, which partially explains why he had to bring her into the cage with him. The other part is that she would have gone on a killing spree otherwise. Before the normal drama could play out, the plot got supernatural, and Oz killed Veruca to prevent her from killing Willow. Oz went away, and Willow went gay.
 * In the episode "Family 8108" from Cold Case, it appeared that the Japanese father cheated on his wife as he caught kissing the school teacher who worked at the internment camp. However, it was averted as that was all they did and the husband told the teacher right away that he loved his wife and the teacher understood. But nevertheless, it spurned his son to join the army out of spite for his father.
 * Finely subverted in The District: The mayor is spotted having discreet meetings with a young Asian-looking woman. Turns out she is
 * In the fifth season of Charmed, Paige briefly dated a guy until she found out he was married with two little children.
 * This is the basis for the ICarly/Victorious Crossover. Carly's boyfriend Steven has been cheating on her with Tori and vice versa, and enjoying it. Carly ends up finding out the truth and teaming up with Tori to humiliate the cheater live on the internet.
 * Both girlfriends Finn has had in Glee have not only cheated with him, but cheated on him with Puck. Also Quinn cheats on Sam with Finn and Brittany cheats on Artie with Santana because Santana convinces her its not cheating because the plumbing is different.
 * New Girl: As part of the show's premise, Jess returns home early in hopes of surprising her live-in boyfriend, only to find him cheating with another woman. This leads to her breakup and search for a new apartment.
 * Niles' wife Maris on Frasier with their marriage counselor of all people, and just a few scant weeks after she had undeservedly managed to cajole Niles into returning to her, to boot. This was particularly devastating to him, since he himself had struggled with an attraction to Daphne for years but always quashed it and remained steadfastly faithful while he and Maris were together.
 * Frasier's wife Lilith also cheated on him back in Cheers right before she dumped him for the man she was cheating on him with, which caused Frasier to nearly commit suicide and earned her several years of unrelenting wrath from Niles and Martin. In a very different spin on this trope, Hester Crane also cheated on Martin decades ago, but the two of them overcame the incident and had an otherwise very happy marriage.
 * Necessary Roughness starts off when Dani finds out that her husband has been having affairs right under her nose and has even been using the guest bedroom in their house for it. She promptly kicks him out of the house and files for divorce.
 * The romantic story arc in Hannah Montana between Miley and  comes to an end in season four, when Oliver takes a photo of  . Oliver and Lilly try to hide this from Miley, but she finds out eventually while shooting a Christmas special she and   from a boy extra who accidentally reveals the secret when Lilly and Oliver are talking to her. She retaliates by beating up   on camera.
 * A season 3 episode has Oliver practice saying "I love you" to an unconscious Miley in the hospital (she injures herself in a skiing accident in the episode's open); Miley's subconscious self overhears him in an out-of-body experience and thinks Oliver is cheating on Lilly with her. Miley's disgust for Oliver (mixed with Lilly's overbearing sadness at finding out, and Miley's flattery that Oliver is attracted to her) are Played for Laughs for much of the rest of the episode, along with Miley's attempts to encourage a still-emotional, makeup-streaked Lilly to find another boyfriend at the beach. Naturally, Lilly and Oliver reconcile, and are upset with Miley.
 * In Good Luck Charlie this happens to Teddy. It turns out Spencer had told Teddy that Skyler was his cousin and vice versa, it doesn't end well for him.
 * The infamous Love Triangle of Arthur, Guinevere and Lancelot is dealt with in a unique way in Merlin. Gwen and Lance were each other's First Love, but because of circumstances they never had a chance to get together properly. Guinevere eventually falls in love and gets engaged to Arthur, only for Morgana to send a Brainwashed Lancelot to the celebrations in order to confuse and upset Guinevere. When Gwen doesn't react to Lancelot's return, Morgana ensures she is Mind Raped by an enchanted bracelet and ends up caught in a compromising situation with him. Even Guinevere doesn't understand why she acted the way she did, and the real tragedy is that she admits that she did once have feelings for Lancelot, as did Lancelot for her - but the audience knows both were too noble and too devoted to Arthur to ever even consider acting upon them.
 * In How I Met Your Mother, Ted's highschool sweetheart Karen, whom he dated off and on throughout college was most notorious for cheating on him constantly, fueling their endless cycle of break-ups and make-ups. This caused Lily and Marshall to develop a vendetta-like hatred of her and give Ted a lot of flack for repeatedly taking her back.
 * In season 7, this happens to  who cheated on their respective girlfriend and boyfriend at the time.
 * The nightmarish situation was nicely summed up as "Well, I'm stuck on a boat with the guy I cheated with, the guy I cheated on, and the girl who the guy I cheated with, cheated on, so no, I'm not doing so good."
 * This was a fairly prominent part of Jackie and Kelso's relationship in That 70's Show. Note nearly all of the affairs are one night stands.
 * Kelso would cheat often and freely without Jackie ever suspecting a thing. One affair in particular - the one with Eric's sister - becomes more a relationship than just a one night stand like the others and is the one he is caught in.
 * Jackie's turn: Later, she kisses The Cheese Guy, which Kelso fails to see the irony in. This is lampshaded:
 * Kelso would cheat often and freely without Jackie ever suspecting a thing. One affair in particular - the one with Eric's sister - becomes more a relationship than just a one night stand like the others and is the one he is caught in.
 * Jackie's turn: Later, she kisses The Cheese Guy, which Kelso fails to see the irony in. This is lampshaded:

Jackie: You used to cheat on me all the time.

Kelso: Yeah? Well, yeah. But you cheated out of hate, and I cheated out of joy."


 * Later still, Jackie and Hyde start dating and Hyde thinks Jackie is cheating on him and in response actually does cheat on her.
 * Once Upon a Time: In the Real World, Mary Margaret (Snow White) and David (Prince Charming) start having an affair while David is married to another woman. They are found out, and Mary is ostracized for it. There is much debate over whether this "counts" as cheating since the two are meant to be together, but as they aren't aware of the fact that they're supposed to be married, it is still cheating.
 * Infidelity and people's attempts to cover up or get revenge for said infidelity is a frequent plot point in Person of Interest.

Music

 * As you might expect, cheating songs are quite common in Country Music.
 * "Your Cheatin' Heart" by Hank Williams is the Trope Namers and provides the quote above.
 * "Lady Down On Love" by Alabama.
 * "The Thunder Rolls" by Garth Brooks.
 * "The Night Will Only Know," another Garth Brooks song, is about two people married to other people who have a one-night stand and end up witnessing a murder.
 * Similarly, Lefty Frizzell's "The Long Black Veil" features a dead narrator who was falsely accused of a murder and chose to hang for the crime rather than reveal his alibi (he'd been with his best friend's wife on the night in question).
 * "In Another's Eyes", a duet by Garth Brooks and Trisha Yearwood (though this one is more about two people who are trying not to cheat).
 * "Revenge of a Middle Aged Woman" by Tracy Byrd.
 * "Lyin' Eyes" by the Eagles.
 * "Carolyn" by Merle Haggard.
 * "Have Mercy" by The Judds.
 * "Heaven's Just A Sin Away" by The Kendalls.
 * "The Night the Lights Went Out in Georgia" by Vicki Lawrence (later revived in a cover by Reba McEntire).
 * "Who's Cheatin' Who" by Charly McClain (later revived in a cover by Alan Jackson)
 * "Jolene" by Dolly Parton (a rare instance of the song being from the point of view of the person about to be cheated on)
 * "Ruby, Don't Take Your Love to Town" by Kenny Rogers.
 * "Should've Said No" by Taylor Swift.
 * "Here's A Quarter (Call Someone Who Cares)" by Travis Tritt.
 * "I May Hate Myself in the Morning" by Lee Ann Womack.
 * "Cheater, Cheater" by Joey + Rory, wherein the female asks why her man was cheating.
 * ...same with "Cheatin'" by Sara Evans.
 * "Does He Love You" by Reba McEntire and Linda Davis is sung by the wife and the 'other woman'.
 * Also by Reba: "Whoever's In New England" and "It's Your Call." Both involve a wife aware of her husband's cheating - the first says, "You'll always have a place to come back to, when whoever's in New England's through with you," and the second has the lover calling the house.
 * And again by Reba: "Little Rock," which involves a woman deciding to cheat because the marriage fires have dwindled.
 * "Before He Cheats" by Carrie Underwood. It went double-platinum.
 * "Stay" by Sugarland and "From a Table Away" by Sunny Sweeney are rare examples from the other woman's POV.
 * "The Way We Make A Broken Heart" by Roseanne Cash is another example from the other woman's POV.
 * Let's face it, we'd be here all day if we listed all the examples in country music.
 * English boy band Big Fun's most famous song, "A Handfull of Promises", deals with a man having a breakdown after he finds out that his girlfriend is cheating on him. And it's a cute, catchy 90's pop song.
 * The Murder Ballad "Matty Groves" revolves around the titular character spending the night with a nobleman's wife, only to have the nobleman himself come home early (thanks to a tattletale servant). The nobleman kills Matty Groves right away, then asks his wife which man she prefers. When she defiantly answers "I'd rather a kiss from dead Matty's lips than you or your finery," he kills her too.
 * "Lips of an Angel" by Hinder (Covered Up by country singer Jack Ingram).
 * "Lying" by Amy Meredith
 * Glasvegas' "It's My Own Cheating Heart That Makes Me Cry," which never quite makes its mind up as to which side it's on (the relationship is certainly screwed, but it's tricky to tell whether it's because he cheated or because he's completely petrified about her cheating, or both, or neither, or...). In a cross between Soundtrack Dissonance and Foreshadowing, it appears in Skins when Naomi And Emily finally get together and Thomas And Pandora reconcile in S3's penultimate episode; by the time they get two episodes into S4 though... well, see the Skins list in Live Action TV above.
 * "Revenge Is Sweeter (Then You Ever Were), Everything I'm Not, Did Ya Think" - The Veronicas
 * "All I Have" - The Veronicas from the perspective of the cheater
 * "The Long Black Veil"
 * "Over the Hills and Far Away," a folk ballad by Gary Moore covered by Nightwish and Thyrfing, has a similar plot to "The Long Black Veil," with the protagonist unable to confess his innocence to a robbery because of spending the night with the wife of his best friend and having to go to prison.
 * Two Wham! songs deal with cheating in various ways -- "Last Christmas" features a protagonist who's just broken up with his partner because his partner cheated on him, but "this year to save" the protagonist "from tears" on Christmas, he'll give his heart "to someone special". Then there's "Careless Whisper", a song where the protagonist is the cheater and is feeling extremely guilty about having done so. ("Guilty feet have got no rhythm", "Should've known better than to cheat a friend/The wasted chance that I've been given", etc.)
 * Duran Duran's 1981 song "Careless Memories" deals with the protagonist's anger at having found out about his partner's cheating on him and how disgusted he is with said partner. He even regards the exchanges of love and devotion that went on during the relationship as "careless memories."
 * "The Other Man" by Canadian band Sloan, based on Chris Murphy's relationship with Feist, who was also dating Andrew Whiteman of Broken Social Scene at the time.
 * My Big Mistake by Delta Goodrem.
 * Kiss N Tell by Kesha.
 * Womanizer by Britney Spears and as being the cheater in He About To Lose Me
 * Vanessa Amorosi: "Sleep With That" and "Blow Me Away".
 * The infamous and massively Memetic Mutation song "El Venao" by Los Cantantes, in which the protagonist tries to fend off all the rumors about his girlfriend cheating with him with many others. Played completely for the lulz.
 * "Lately" by Stevie Wonder.
 * "Save It For The Bedroom" by You Me At Six is another example where the singer is the one cheating: "Keep your hands to yourself,these lips belong to someone else..."
 * "Escape (The Pina Colada Song)" is a strange example. A man decides to cheat on his wife with an unknown woman who posted an ad in the paper looking for romance. He arranges to meet with her by sending a reply message to the paper, and when he reaches the rendezvous, he discovers that the woman he plans to cheat on his wife with is... his wife. Strangely, catching each other trying to cheat on each other revitalizes their marriage instead of destroying it.

Myth And Legend

 * Pick a Greek myth. Any Greek myth. From Zeus (married to his sister, Hera) seducing or outright raping everyone, male or female, to Aphrodite (married to long-suffering Hephaestus) and her relationship with Ares, to Paris eloping with Helen of Troy, the wife of Menelaus... no wonder there were so many children of questionable parentage running around.
 * Over in Norse mythology, we have Sif- married to Thor, and though it was never confirmed to be true or false, Loki at one point accused her of sleeping with him ("Only I know, as I think I do know/Your love besides Thor/And that was the wicked Loki!"). She says nothing, and then another goddess starts talking. And in an earlier myth, Odin (in disguise) said to Thor the equivalent of "Hey, no need to hurry home to your wife or anything, because she's got someone else to keep her bed warm!" Both times, Thor was understandably pissed.

Theatre

 * In Street Scene, Mrs. Maurrant is Cheating with the Milkman, who the neighbors point out is himself married with two children. Her daughter Rose is aggressively propositioned by her boss, Harry Easter, who tells her that his wife doesn't need to know about anything he's planning.
 * In Chicago, Roxie is cheating on her husband Amos with Fred Casely, a married man whom she shoots to death at the start of the play; Amos grudgingly stands by his wife until she decides to draw sympathy in her murder trial by pretending to be pregnant. The musical also has Cell Block Tango, which contains a minimum of four affairs, depending on how you count it.
 * In Rodgers and Hammerstein's Allegro, when Joe moves to the big city, it turns out that his wife is cheating on him with Lansdale, the benefactor of the hospital he works for. He finds this out from Mrs. Lansdale.
 * In Noh theatre, the bridge princess youkai is the eternally-jealous spirit of a noblewoman whose husband cheated her. Depending on the retelling, she either murdered or cursed him, and the gods turned her into a bridge-haunting youkai as punishment.

Video Games

 * You can accidentally (or not) do this in Dragon Age Origins. Picking any of the more flirtatious dialogue options with a potential Love Interest will make them think you're in a relationship. If you're already involved with someone, you'll eventually be forced to choose; losing approval with the one you give up.
 * If a female PC woos Alistair, they can stay together. Alternatively, if a female human noble , but romanced Zevran, the same situation can happen in reverse. In both cases, it's an affair out of a political marriage, rather than a romantic relationship, which has different implications.
 * As a male Warden, you can exploit a glitch that allows you to be in a relationship with both Morrigan and Leliana, even after you're supposed to have chosen only one of them.
 * Chandra volunteered her eternal love to Karim if he could get his hands on a certain treasure. This one ends tragically for both of them.
 * You can do this in Mass Effect 2, if you romanced someone in both games. There are ramifications for being unfaithful in the third game, though the nature and severity of the consequences depends on the characters involved. Ashley takes Shepard cheating on her with Tali very well, for instance.
 * Actually, despite being promised the consequences for cheating would be severe, no one actually cares if Shepard cheated on them. You still can't have any threesomes but there's no hard feelings. Shepard's just that good.
 * Jacob Taylor
 * In Grand Theft Auto 4, Mallorie Bardas cheats on her boyfriend, Roman, with Vlad Glebov. Roman is OK with it, but his cousin, Niko, is not, and kills Vlad.
 * Roman himself states sleeping with different women during the course of their relationship. While he eventually stops cheating on Mallorie, his favourite activity is still visiting strip clubs.
 * This is Battler's reason for disowning his father Rudolf in Umineko no Naku Koro ni: almost immediately after Asumu's death, Rudolf engaged himself to his business partner Kyrie, who was already pregnant with Ange.
 * This is what kick-starts the plot of Catherine.
 * This happens in every route except  in Symphonic Rain
 * Persona 3 requires you to max out various "social links" to get the best ending. Unfortunately, all of the social links with girls your age (or with most of the guys if you pick the female protagonist in the PSP remake) involve dating them and imply sleeping with them when you max them out. This trope is played straight in that the girls will get jealous if you date multiple girls at once, but is subverted in the end because once you reach the ending of a social link, you're free to go after another girl with no threat of breaking the link.
 * There's also a great scene added to Persona 3: FES where all the girls you are dating at school almost figure out what's going on and almost corner him while setting up for the school festival.
 * The female protagonist can actually get two party members to bicker over her in combat if she maxes out social links with them. Oddly enough, she has an easier time cheating because she doesn't have to worry about reversed S.Links from running around like the male character does despite no one ever mentioning it outside of the above mentioned bonus scene from FES.
 * Persona 4 uses the same social link mechanic, but you're given the option of keeping your friendships with the girls platonic and pursuing only one or no girls. However, you also have the option of sleeping with them all if you do it right.
 * The game In the 1st Degree has this happen. To start, you have Zachery Barnes and his wife Yvonne Barnes, as well as James Tobin and his girlfriend Ruby Garcia. Yvonne has been very focused on her career, leaving Zach unhappy. Tobin has slept around, and even told Ruby that he is only interested in getting into her pants, leaving Ruby unhappy. As a result, Zach and Ruby had an affair. There were reprecussions from this. First, Zach wrote a love letter to Ruby admitting that he loves her, but he is convinced that the affair should not have happened. Second, Tobin found out about the affair and was furious over it, giving him one more reason to murder Zach. Third, . Now that is drama!
 * In LA Noire there's a few cheating couples in the various missions but more prominently is
 * In Katawa Shoujo,
 * Chandra in Eternal Darkness sends Karim on a fool's errand to retrieve an Artifact of Doom for her, promising to wait only for him. He's gone long enough that she "gives herself to a nobleman with a jealous mistress" and is murdered for her infidelity. She and Karim end up being Together in Death.
 * In Culpa Innata, the citizens of the World Union are encouraged to avoid romantic attachments. Marriage (or rather "nuptial agreements") are not permissible for Union citizens. They are, however, allowed to have primary sexual partners, which means absolutely nothing from a legal (or personal) standpoint. During the game, one of the potential Union citizens is an Indian immigrant, who reveals that he has cheated on his wife on several occasions and doesn't feel guilty about it (he's also ), while his wife never did because of the social Double Standard in Indian culture.

Webcomics

 * The issue of just what constitutes cheating was raised in Friendly Hostility. Fox is devoted to his boyfriend, Collin, but his bisexual colleague Derringer springs a kiss on him, just to see what it's like. Fox is outraged. However, he's even more outraged when Derringer questions Fox's kissing skills... and so Fox kisses him again to prove his aptitude. On the Friendly Hostility blog (doubling as The Rant), fans varied between "kissing is cheating" to "it was just a kiss" to "kissing usually counts, but there was no affection behind it, so it doesn't." Some fans even suggested that it might be good for Fox and Collin to break up following this incident, since they didn't think it was psychologically healthy for Collin to only have one romantic/sexual partner in his lifetime and he needed to "see other people" rather than remain exclusive to Fox.
 * Nerf Now had cheating on  with, after an argument.  later produced ambiguous evidence that.
 * apparently cheated on Davan of Something Positive several times while they were together, before he finally caught her doing it with her abusive ex-boyfriend.

Western Animation

 * On Total Drama World Tour, Duncan cheats on Courtney by kissing their mutual friend Gwen, leading to much drama during the rest of the season.
 * On Daria, Daria and Tom kiss while Tom is dating Daria's best friend Jane.
 * It's implied that both Brittany and Kevin have cheated on each other at various times, though this is Played for Laughs.
 * On King of the Hill, Nancy cheated on her husband Dale for years with John Redcorn. Despite being a paranoid conspiracy nut, Dale never even figured out that their clearly Native American son wasn't his (though he does believe he was conceived by alien in-vitro, since he wasn't even home around the time of conception). The twist is that everyone else knows about the affair. They all just don't tell Dale because they want to spare his feelings and they know Nancy still loves Dale despite her cheating.
 * Also, Buck Strickland cheats on his wife. Quite a lot, in fact.
 * On The Simpsons, Apu cheated on his wife Manjula. Averted with Homer and Marge; both have had opportunities and temptations to cheat, but have racked up quite a few Crowning Moments Of Heartwarming by sticking together.
 * One episode reveals that Mona was cheating on Abe around the time of Homer's conception, leading to questions about whether or not he was the father. It turns out.
 * Homer's half-brother Herb Powell is the product of an affair between Abe and a woman who worked at a carnival.
 * On South Park, Butters' dad cheated on his mom with numerous gay men, leading her to go crazy and plan to kill herself and Butters.
 * Cartman was conceived from an affair between his mother and . Also implied between her and Kyle's dad Gerald, another potential father, though in another episode he's apparently fine with his wife sleeping with Chef, implying they may have an open marriage.
 * A really messed up example occurs in the Ren and Stimpy episode, Ren's Brain. Ren, who was at the time a disembodied brain and unaware of it, comes home from work to find Stimpy sitting with Ren's body. Cue Ren's brain having a Freak-Out, accusing Stimpy of " Entertaining another chihuahua", calling his body a "homewrecker", all culminating in the viewers' heads exploding, then the Earth itself explodes and Ren's brain is seen floating off into space yelliing "YOU EEDIOT!"
 * Terry McGinnis has a girlfriend throughout the entirety of the series and the movie. Yet on several occasions he spends quality time with 10 of the Royal Flush Gang.
 * However the first time was when he and Dana were broken up.