Designated Love Interest

A character in a story who, despite being presented as the One True Love of a central character, doesn't seem to have much of a relationship with said character at all. The catalyst for the relationship appeared off-screen before the series began, and save for maybe an occasional over-the-top gesture, never really appears to manifest. This isn't a matter of their love being subtle- it's more like they just kind of know each other but since he's a dude and she's a chick, they must have some sort of romantic attachment to each other because it's a law of the universe that opposite-sex-characters are always involved in romantic entanglements. Ultimately, this is a romance of necessity, not in the literal sense, but because of the assumption that the story needs a romantic plot or sub-plot to move forward.

Other characters will usually acknowledge these relationships, but not say much else about them. Sometimes one may even get in a What Does She See in Him line in, though this is relatively rare. There's usually some sort of plot or setting-related reason why a character needs a significant other at this point in time, and it would be bad form for a character to openly question what they even have in common. A Shipper On Deck will have no issues with getting people together despite lack of any real logic behind it, and in extremes cases entire casts may get on this bandwagon.

This trope most commonly appears in action-adventure stories where the writer, having little experience writing actual romances, doesn't have any idea how to do it subtly. Alternately, he may just not want to since romantic Character Development drastically cuts down on the time available for random explosions.

Compare and contrast Strangled By the Red String, where the relationship goes beyond "plot convenience" to "acknowledge this as being true love dammit!" Contrast Shallow Love Interest, in which the character is all about being the love interest and nothing else, rather than having characterization that doesn't fit being a love interest.

Anime

 * Rumiko Takahashi, author of Ranma One Half, Inu Yasha, and Urusei Yatsura, is especially guilty of introducing characters just to pair up with other characters, then forgetting about them. Usually, they make a token appearance and then are never heard from again, or perhaps two or three times at best. Her justifications have driven away many former fans; she has stated on multiples occasions that she only creates some characters to attempt to deter fans from inventing pairings she didn't intend.
 * Ranma One Half... first of all, there's Akari Unryu; apparently, the demand for Ryoga to get a happy ending led to the creation of this girl, who is so perfect for Ryoga, and shows up so few times in her subsequent appearances that she has been derided as a Canon Sue Relationship Sue.
 * Mousse got some major attempts at redeeming his character, which can actually come off as rather jarring due to the fact he spent the early series trying to kill Ranma; and once boasted along the lines that he would gladly break any rules and forsake any honor to get Shampoo, though Shampoo never changed her opinion of him- while she did occasionally show him some "soft" moments, she spent most of the series outright abusing him and, on one occasion, was perfectly willing to go and play videogames while abandoning him to what she believed would be certain death at the hands of a life-sapping demon.
 * Ukyo got an (attempted) and very literal Last Minute Hookup in the form of an effeminate transvestite ninja master, who appeared less than Akari did.
 * Urusei Yatsura is a case where this might actually be the happy ending; initially, Shinobu, the Tsundere with Super Strength, seems to be the Unlucky Childhood Friend, though she legitimately falls out of love with Ataru Moroboshi due to recognizing that he is an apparently irredeemable Lovable Sex Maniac... her next choice of crushes? Handsome Lech and Royal Brat Shuutaro Mendo, who's not only just as bad as Ataru in terms of lustfulness, but is also chasing after Cute Monster Girl Lum. Meanwhile, she's being pursued by the gonkiest character in the series, a hulking, repulsive moron who repeatedly tries to ambush her. Finally, she earns the attention of Inaba, a shy and clumsy, but sweet, innocent and genuinely romantic character, whom she grows quite fond of. And then he only shows up in about one story...
 * Ryuunosuke has a similar case happen to her at the end of the manga. Towards the end of the manga, she gets betrothed by her father to Nagisa, the cross-dressing son of her father's friend. Nagisa however, only appears in two two-part storylines in the manga, and an OVA, and the big manga finale.
 * To some, the Ship Tease she added in with Sesshomaru and Kagura can come off as an attempt to deter the fandom from shipping him with Rin.
 * Usagi and Mamoru in Sailor Moon's animated adaptation. During one of The Movies, Usagi is slightly depressed that she has no idea what Mamoru is like, can't have a conversation with him, and doesn't even understand his interests. Their later failures to really interact with each other may have to do with the television writers not finding him very interesting, aside from a character for her to emote at -- which is really his fundamental purpose, after all.
 * While Cain of Count Cain flirts with (and presumably sleeps with) as many women as possible throughout the series, when he finally gets paired up with it feels ridiculous, since she's just as vapid as any other woman he's met and slept with. She has nothing to distinguish her; she is the least unique character in the entire series. Even the author admitted that the fans didn't like her; she seemed surprised.
 * A lot of yaoi works fall squarely into this trope, as most are focused on getting the Seme and Uke into bed together as soon and often as possible and don't bother developing their personalities or relationship beyond "they're hot and readers want to see them boinking each other, so let's have the cool Seme fall in Love At First Sight with the cute Uke and/or rape him at the first opportunity to get to the sexytimes ASAP". The same could be said of many of the shorter and smuttier Josei stories, and frankly any "erotic romance" genre regardless of the sexes of the characters or readers.

Comic Books

 * Played straight in Brand New Day Spider Man with Carlie Cooper. Everyone, including Mary Jane, is trying to get her together with Peter and gushing about how perfect and wonderful for him she is. Too bad she hasn't really done much to live up to that hype.
 * To expand, the major problem that started with the pairing is that each writer seemed to have their own take on who should end up with Pete in Brand New Day. Dan Slott was in the Carlie Cooper camp, Mark Waid focused on Pete and Michelle, and Joe Kelly always had Peter and Norah. The latter two actually went through lengths actually showing the chemistry while Slott spent more time simply presenting Carlie as the perfect match. Now that Carlie has hooked up with Peter time will tell on whether or not this trope will still stick.
 * Time for some Squick: Joe Quesada invented Carlie Cooper solely so he could sink the Peter/Mary Jane ship. Who did he base Cooper on? His own daughter!
 * Spider-Island put an end to all of that.
 * The Page Sisters from Jack Of Fables . Despite showing no interest in the main character and outright despising him, all three ended up sleeping with him more than once. It got especially bad when Robin, who had spent the previous issues hating Jack with a passion, had no problem with the idea of a foursome. It then becomes outright horrifying when it's revealed that.

Film

 * The romance in Underworld. There is never any indication that Selene feels any real emotion toward her intended hookup; they have yet to actually have any sort of conversation with each other about anything apart from vampires and werewolves and they have known each other for a total of about two days. Word of God says this was the way it was supposed to be- special Features on the Underworld DVD reveal that the two characters were not supposed to actually be "in love," but rather attracted to each other based on lust, confused feelings and being forced together.
 * Avatar. The romance between Jake Sully and Neytiri is given almost no real buildup and no reason beyond, "Hey, they've been spending a lot of time together and Jake needs a way to get into that culture. Let's hook them up because that is What Those Types of Characters Do."
 * The 2005 Alone in The Dark. The Love Interest never added anything of value to begin with, and the romance itself comes completely out of the blue. Sadly, by the end the Romantic Plot Tumor is the only thing keeping the plot moving forward.
 * Averted in Hot Fuzz. Early drafts of the script had a love interest for Nick called Victoria. Because she was boring, slowed down the plot and had nothing much to do by the finale they instead cut her out and gave a fair bit of her dialogue, often unedited, to Nick's burgeoning Heterosexual Life Partners Danny.
 * The Breakfast Club: The end of the movie hookups . While the characters have clear moments of bonding and all of them growing closer to each other is the whole point of the movie, it's made a little tough to believe due to how much of the film they all spend abusing each other, and no, abuse in the case does not mean Unresolved Sexual Tension; it means abuse.
 * Enchanted lampshades the prevalence of this trope; Giselle and Edward start out madly in love with each other without any actual reason for why. It's just how things work in the fairytale land of Andalasia.
 * In-story of Watchmen, this was practically Laurie's job, being Dr Manhattan's lover. And he likely only loved her because he could see himself doing that in the future. Also, during production of the movie someone tried to write in a non-canonical love interest for Rorschach. It was changed when people realized how utterly out of character that would be.
 * Ginny Weasley in Harry Potter. Harry and Ginny barely interact, sharing the screen for about seven minutes combined in the last three movies. Whenever they are on screen together, they barely talk, instead just sharing a kiss and an awkward look before Harry rushes off to do something and Ginny sits down to be irrelevant to the plot.
 * In the end of Thor, he ends up kissing the female protagonist and vowing to return to her. He helped her out through out the movie, but other than that, there's really nothing that led up to this other than "because she is the love interest"

Literature

 * Edward and Bella from Twilight. Edward acts surly and moody toward Bella for the first half of the book, and yet Bella decides that she's "unconditionally and irrevocably in love with [Edward]" right after she realizes that he's a vampire who thirsts after her blood, and is completely devoted to him from that point on, even in the face of Edward's own warnings about how he could kill her. Just how devoted is she? She's willing to give up her human life without any second thoughts to be with him forever after what can't be any more than a month of knowing him, and instantly leaps back into his arms after he renders her practically comatose by leaving her without explanation. And her interactions with Edward after the vampire "reveal" consist almost entirely of them repeatedly professing their love to one another and her even more repeatedly being "dazzled" by Edward's glorious beauty. And let's not start talking about the werewolves who have an "imprinting" mechanism that causes them to fall for each other soon after they're born (essentially the opposite of the well-documented Westermarck effect).
 * An even more shallow version happens in The Short Second Life of Bree Tanner, with Bree and Diego and, later, Freddie. Bree and Diego interact for one night, she spends most of it afraid that he's going to kill her, and by morning they seemingly are madly in love with each other. The same goes for Freddie. Since it's from Bree's point of view and the "relationships" between her and the guys are so muted, it's possible that we're supposed to see it as her mistaking simple friendship for love (which would fit with her background of being abused and neglected), except that nothing ever indicates this and she acts almost exactly the same way Bella does, including
 * House of Stairs defies this in the end. The last two protagonists get out of the building, and they're walking together and holding hands. The male lead then spends a paragraph lecturing the reader on how not all inter-gender relationships are sexual. Anvilicious, perhaps, but probably necessary given how common this trope is.
 * Ginny Weasley from the Harry Potter series. Part of the hate for the pairing is because of Die for Our Ship, while the other part is rooted specifically to this. After her questionably rushed hook-up with Harry, most of the development of the pairing took place off screen. In fact, there's a time skip following their hookup where Harry described it at as some of the happiest moments in his life, but the reader never actually get to see it.
 * Part of the reason Ginny isn't liked is because really, most of her best moments don't get to be seen; other characters say she managed to do this impressive thing or is really popular, but this never seems to happen around Harry. (J.K.'s explanation is because she's still shy around him.)
 * The film version of Half-Blood Prince manages to avert this somewhat by expanding Ginny's screen time and giving her more sequences alone with Harry.
 * Aragorn and Arwen in The Lord of the Rings - justified somewhat as the story is primarily told from the Hobbits' point of view and they weren't around when they fell in love etc. years earlier; the story is only concisely dealt with in one of the appendices. This has led to quite a number of readers favouring Eowyn's hopeless love for Aragorn.
 * Les Misérables gives us Marius and Cosette. Seen each other from afar and are madly in love with each other (at least after Marius noticed Cosette being grown up. Make of that what you will). To be fair they get time to groom their relationship... with Cosette listening to Marius' political views. Well, we have to count in the Values Dissonance here too. But still...
 * The Hunchback of Notre Dame by the same author also shows how awful this can end in so many, many ways.

Live Action TV

 * Kate in season one of White Collar. It would have been nice to see the one woman who made Neal Caffrey want to commit; unfortunately, Kate is not given a personality, motivation, or even charm. With no material to work with, the role was also tragically miscast with an actress who seems too sweet. In short, she's far too bland to pull off the unforgettable Woman in White or One True Love that Neal keeps saying she is.
 * Almost every relationship in Heroes, especially in the second season. Notably Peter/Simone, Maya/Sylar, Peter/Caitlin, Hiro/Yaeko, and Claire/West. Luckily, they seem to have given up. Played extremely straight with, in which a psychic vision convinces one character he's "supposed" to be with another. Unsurprisingly his "love" is skeptical and although she plays along she frequently points out how this is not any sort of basis for a real relationship.
 * Rodney McKay, repeatedly, in the last two seasons of Stargate Atlantis. The first major girlfriend, Katie Brown, was a drippy botanist that he had nothing in common with whatsoever, and the second was Jennifer Keller, who had previously seemed to have a nice thing going on with Ronon. This may have had something to do with the fact that the most popular ship in the entire fandom was McKay/Sheppard. In the episode The Shrine, after all of one episode of any serious interaction, he's declaring his love for Keller in a video recording.
 * Lancelot and Guinevere from Merlin. It's an inevitable pairing, but it moves like a runaway train. She fits him for a suit of armour and he kisses her hand. That's the last time they interact for a year, and then their paths cross again whilst Guinevere is held captive in a warlord's castle. Lancelot helps her escape, during which he tells her (and others): "I would die for you ten thousand times over," "She means more to me than you will ever understand" and "tell her that she's changed me forever." All this on the basis of two short conversations. Still, some say that the chemistry of the actors makes up for it...
 * Kate from Robin Hood was introduced into the show as a Replacement Scrappy for Marian, a Replacement Love Interest for Robin, and the Designated Victim to the outlaws. She has little in the way of personality, does virtually nothing but pursue Robin, and is utterly superfluous to the plot. At the end of the series Robin is killed off to be reunited with Marian and the writers immediately start pushing Kate toward Robin's Replacement Scrappy, his half-brother Archer. Oy.

Opera

 * Common legend has it that during Puccini's writing of Turandot, he supposedly abandoned it before the end because he was unable to justify Calaf being in love with the psychotic, man-hating ice queen Turandot when the pure-hearted slave girl, Liu, had remained loyal to him for so long. He had apparently wanted Calaf to fall in love with and marry Liu, whereas the libretto (as well as the story the libretto was based on) had Liu tortured to suicide, after which Calaf then marries Turandot. After his death, the opera was eventually completed by one of his students. However, this is demonstrably false, as the real reason it was never finished was that Puccini had laryngeal cancer and died before he could finish. That this legend lives on shows how most people think of the story's couple, and it has been famously criticized by scholars for the rushed attempt to pair Calaf and Turandot.

Pornography

 * From movies to Hentai to "erotic stories," this is so common that is it to be expected. Granted, most of them don't have any sort of story, but even in the ones that have a story or are based on a story (usually hentai versions of a popular Anime), two characters suddenly jump at each other, even if they clearly had a different personality or sexuality that would not allow this pairing. (Or often, more-than-pair...ing.) And if it actually has enough of a story to have side characters, they will act like nothing surprising happened and this is completely normal and will act as before after the sex is over. (If there is an "after the sex is over" part of the story.) Aversions are so rare that if character development actually happens, one could follow the story for the surprise value and ignore the fact that it's porn.

Theater

 * Lampshaded by Friar Lawrence in Romeo and Juliet as Romeo falling for Juliet to the point of wanting to marry her so soon after breaking up with Rosaline. "Young men's love lies not in their hearts but in their eyes."

Video Games

 * Serge and Kid of Chrono Cross. The player can have Serge treat Kid like crap, ignore her at every turn, leave her to die a slow death by poison, stab her in the chest, apparently use and manipulate her and then kill her again, and finally leave her in a coma reliving the single most traumatic day of her life, and she'll still be in love with a man she barely knows who already has a girlfriend. Her only mandatory interactions with Serge come from the manipulations of another character. Yet even after the ending of the game apparently presses the Reset Button on the entire series of events, she's apparently so in love with Serge that she will promise to find him and the game completely ignores the fact that, again, he already has a girlfriend. The game treats this as a cherished romance and there's even concept art depicting a married Serge and Kid. Bet there's going to be some really awkward stories to tell the children...
 * Polka and Allegretto of Eternal Sonata have very little chemistry together. Over the course of the game, Polka spends more time (and has more chemistry) with Chopin. But since he's a) old enough to be her father, and b) dying, they shove her together with Allegretto at the end.
 * Asbel and Cheria in Tales of Graces. Other characters constantly tell you that they'd make a really cute couple (to which they get the usual reaction), but Asbel and Cheria don't actually get along that well. They're childhood friends, but due to being apart for seven years, they've grown distant. Cheria regularly tells Asbel that she doesn't like him, which visibly upsets him. When Asbel tells Cheria that this hurts him, she blows up at him again and refuses to apologize. Their entire relationship is a string of failed communications, and they only get together because other characters (especially Sophie and Frederick) play matchmaker for them.
 * While Persona 3 allows you to choose your romance amongst the various females, Yukari Takeba is the only one whose romance intertwines with the actual story. This cause several Ship Tease moments with a character you may choose not to pursue their Character Arc with.
 * Other fans will point out that Aigis, a Robot Girl with Stalker With a Crush tendencies, also qualifies. While she is important to the Protagonist's backstory, the latter half of the game seems to focus on her. Which, if you don't even think of her as a Love Interest, comes off as forced. The fact that she is  It does explain why, the next game in the series toned down on the female interaction, with only minor optional flirting in the main plot.
 * Similarly, Dragon Quest V gives you the choice of two heroines, three on the DS remake, but the game almost forces Bianca on you, even having some nasty Player Punches if you pick the other girl, though thankfully the worst one was removed in the PS 2 and DS versions. That said, the other girls aren't that much more developed either, but at least the game doesn't shove them on your face.
 * Megan Reed is this to Adam Jensen in Deus Ex Human Revolution. Their entire relationship (including a break-up) took place prior to the events of the game, but the game seems to be insistent on playing Adam like he's still carrying a torch and his main motivation is to avenge her death from the shadow conspiracy.

Web Comics

 * Ethan and Lilah from Ctrl Alt Del. The only reason why the two characters got married seems to be that she's the only main character who is a woman.
 * Beth and Fisk from Better Days fall into this. Never do we see the characters discussing their hopes, dreams, or fears together. They become sex friends about a day after they meet with little provocation. Then while Fisk is serving his time in the military, Beth somehow falls deeper in love with him during his absence. Even though she is actively dating two other men who are more financially secure, physically and emotionally available to her than Fisk is. If they aren't having sex then they are talking to each other in bed right after sex but it's never about anything important. Sans one time when Beth desperately wants Fisk to live with her, these two characters never express how much they supposedly mean to each other and the reader is supposed to assume that their relationship is deeper than just their sex drive. She does eventually give up on him and settled down with her boyfriend Aron instead, so this could arguably be a Deconstruction of the whole concept.
 * Less when there's a few lines about how Beth and Fisk broke up because she 'wouldn't accept his job'. Except....that wasn't what happened at all. Beth asked Fisk to make their relationship more than sex, a huge risk for her, and he decided to accept his much-hated assassination job. Beth never said she didn't accept the job, or indicated she knew what the job actually was at all, only that the guy who said he'd live with her suddenly said he wouldn't to go do a job he had no desire to do a week before.
 * Kevin and Kell featured longtime character Rhonda getting Put On a Bus by marrying her online boyfriend, who was first mentioned and introduced in the strip merely days before this event took place. Up until that point, Rhonda had been dating Edgar since high school and the previous year had even featured a story arc where Edgar humiliated himself trying to learn how to hunt to show that he cared more about Rhonda's acceptance than his own species'. The previous plotline had taken several weeks to resolve, while Rhonda's marriage and subsequent disappearance from the strip happened over only one week. On top of that, this led to another plotline with Edgar learning how to hunt to get Rhonda back.
 * Name a pairing from Sonichu. Virtually everyone in the series paired off with very little reasoning. Sonichu fell in love with Rosechu after meeting for a few seconds. Bubbles fell for Blake for some unknown reason. Everyone else? Paired off in mandatory dating classes!

Western Animation

 * Gwen and Kevin in Ben 10 Alien Force -- The ship is dropped on the viewer with absolutely no set-up, no basis, no rationality in the very first episode. Kevin almost wrecking his precious car to tell Ben not to be rude to Gwen could be attributed to his Badass Decay, but "I'll follow you anywhere"? Were the writers afraid that if they took the time for some actual development, the show might be canceled before their new favorite couple actually got together? Ben's relationship with the new character Julie is hardly any better.
 * From Gargoyles, Elisa and Goliath could be considered this in season three. The build-up went well for two seasons, culminating in a kiss in the second season finale and a date in the third season premiere (well, a planned date that got aborted by attempted murder, anyway). After that any overt romance disappears, save for an All Just a Dream episode where they're married. In this case the problem was Executive Meddling--the creator, Greg Weisman, had been booted from the show, and as a result every episode after the premiere is Canon Dis Continuity; the comic book Post Script Season that replaces it does, in fact, deal with the implications of their hook-up.
 * In Wolverine and The X-Men, Jean is this to Scott. Despite having developed a relationship with Emma Frost (which was surprisingly well-done for a children's show) he still ends up going with Jean Grey (who we hardly see with Scott because she spends much of the first season without her memory) just because it's in the comic's continuity. Maybe we would've seen them together more if the show got a second season, but as of the first and only season, Jean is the Designated Love Interest.
 * In Batman Beyond, Dana was Terry's girlfriend from before the series started and is continuously Terry's girlfriend for the entire run of the series. However, the audience doesn't really get to see much onscreen romance between the two due to the series's focus on superhero action and Dana's lack of screentime. Most of the time their romance is shown either by being arm-in-arm when together, or when Terry has to break a date. In the later episodes, Dana gets Demoted to Extra as Max fills her role of a normal person that Terry talks to.