Divorce Is Temporary

""You've got an old-fashioned idea divorce is something that lasts forever, 'til death do us part.' Why, divorce doesn't mean anything nowadays, Hildy, just a few words mumbled over you by a judge.""

- Cary Grant, His Girl Friday

In real life, divorce is usually a permanent and messy affair. Not so much in fiction. If the parents are already split by the beginning, then all it takes is some bonding and bam they're together again. Getting married again is not a requirement, they just need renew their romantic relationship.

Of course this has Unfortunate Implications in the form of the Broken Aesop that people who get divorced don't really mean it, and all it takes is a little work to fix a relationship. The pervasiveness of this in pop culture can give children of divorced families false hope and an unrealistic view of their parents relationship and the new dynamic of their family, also making it a Family-Unfriendly Aesop.

All that said, it does sometimes happen in Real Life. A story involving reversing a divorce can be done well and even be realistic, though it requires skill.

Alternatively, it can also be family-friendly Aesop about how relationships need more than romance to work. But most of the time the re-pairing is due to renewed romance, and tends to leave the real problems that led to the divorce unresolved.

See also First Father Wins for the fate of anyone new the mom dates post divorce. Compare Comedy of Remarriage. Often brought about by a Parent Trap Plot.

As this is a ending trope, Unmarked Spoilers Ahead!

Film

 * In both versions of The Parent Trap, the twins actively invoke this.
 * In Mr Poppers Penguins the titular animal-owner seems to be rekindling his relationship with his ex-wife and the mother of his children as a result of the animals' humanizing influence.
 * What a Girl Wants plays this with Libby and Henry. Apparently nearly twenty years of estrangement can be fixed with one magical evening at the ball. Justified in that the split was due to a lie of Henry's Evil Mentor rather than any actual problems between the two, and once said mentor is out of the picture they can try again without his interference.
 * In Liar Liar, Fletcher and Audrey get back together in the final scene. They of course ask their son if he made another birthday wish to cause it.
 * Troop Beverly Hills ends with Fred seeing Phyllis's dedication to the scout troop, and realized she was not so "flighty" after all.
 * Intentionally subverted with Mrs. Doubtfire. The executives wanted a happy ending, but the writers felt it would be a disservice to real children with divorced parents and pulled a Writer Revolt. The film even ends with a voiceover stating that sometimes divorced parents get back together... but sometimes divorce is really the best option for everyone involved.
 * Taken to extremes in The Marrying Man where a guy marries the same woman four times.
 * In Outbreak Daniels and Robby start the film divorced but end it reconciled.
 * In The Day After Tomorrow Jack and Lucy Hall start the film divorced but end it moving toward reconciliation after Jack risks his life to rescue their son from frozen New York.
 * In Independence Day, David realizes the aliens are planning to attack. He enlists his father to drive him from New York City to Washington, DC so he can warn the President. David's ex-wife Constance happens to be the President's aide. By the end of the film, David is a hero who's helped saved the world, and he and Connie are on the road to reconciliation.
 * The hero of 2012 and his wife also reconcile, due to her Love Interest failing to survive just as they finally make it to safety.
 * In Definitely Maybe, this is played with in that Maya believes in this trope, but it's eventually averted and she accepts that her father (played by Ryan Reynolds) and her mother won't get back together.
 * She's the Man has Viola's parents getting back together after the final soccer game, despite spending years apart.
 * The ending of Crazy Stupid Love implies that Cal and Emily may get back together, or at least stay good friends. What makes this complicated (and is unaddressed at the end) is that Emily may or may not still be dating the guy with whom she cheated on Cal in the first place and Cal having.

Literature

 * Judy Blume often Subverts this in her novels. They are known for being painfully realistic, and not to mention highly controversial.
 * Averted in Dear Mr. Henshaw by Beverly Cleary, although Leigh desperately wants his parents to get back together and there are still feelings on both sides, his mom refuses, because she knows it will only end the same way.

Live Action Television

 * The Odd Couple: One of the premises of the Neil Simon comedy was that both male leads – Felix Unger and Oscar Madison – were divorced, although both try to win back their ex-wives. For Felix (at least in the TV adaptation), his divorce from ex-wife Gloria was temporary ... and the two were re-married in the series' finale, aptly titled "Felix Remarries."
 * Pretty Little Liars with Aria's parents, though they were separated rather than divorced.
 * Averted on The Wire. In a season 3 episode Mc Nulty and his ex-wife have a passionate one night stand, the next morning he thinks they're back together but she insists that its just a one time thing and they never get back together for the remainder of the series.
 * Entourage had a last season arc involving Ari and Mrs. Ari being separated, and eventually her asking for a divorce. Eventually Ari realizes that shock, it's not Ari himself that she wants the divorce from, but the fact he has become an absentee father and husband because of his career. When he finally figures it out, he ditches work and she takes him back.
 * In The Secret Life of the American Teenager, Amy's parents get back together for a while, but split up again. They're still good friends at the end of the series.
 * In Twenty Four, Tony and Michelle are divorced between Seasons 3 and 4 due to Tony's becoming an alcoholic after being sent to prison and losing his job over betraying CTU to save Michelle. After the events of Season 4, they're back together.
 * Played with in Frasier. Niles and Maris break up and get back together at least twice with Aw, Look -- They Really Do Love Each Other overtones, but this is retroactively depicted as a bad idea. It's acknowledged that Niles went back to Maris because of insecurity and self-delusion, and that they should have stayed broken up. When they divorce, they again threaten to backslide several times, but in the end it's for keeps.
 * Frasier and Lilith tend to play with this idea throughout the show, but nothing ever comes of it.
 * The Sopranos pulls this without even getting to the divorce. Season 4 ends with a violent confrontation between Tony and Carmella and she insists that they separate. A season later he's Out-Gambitted her in the divorce proceedings because he's talked to most of the major divorce attorneys in town and the others won't take Carmella's case because of Tony's reputation. Later on he wins her back and they stay together for the rest of the series.

Western Animation

 * The Simpsons: Milhouse's parents get divorced, then several seasons later get back together.
 * Which is within a few months at most.
 * An early episode of South Park played out this plot with Randy and Sharon Marsh. Within a few days, they break up, Randy moves out and Sharon remarries. By the end of the episode, Randy and Sharon are back together like nothing ever happened. The speed itself is what's Played for Laughs, since Sharon practically tells Stan about the divorce in the same sentence when she introduces his new stepfather, while Randy has already embraced a midlife-crisis style bachelor's lifestyle.
 * Same trope gets played with the same characters, albeit in more dramatic fashion, in season 15's "You're Getting Old" which features Randy and Sharon breaking up and moving into separate residences. The next episode sees them get back together, but this arguably deconstructs the trope as one scene has Sharon explain to Stan that sometimes people have to stick with what they know even if it makes them unhappy. It's obvious that this particular Reset Button deeply upsets Stan.

Real Life

 * Eddie Guerrero and his wife never got divorced, but they did separate for several years (during which time he had a daughter with another woman), then when they got back together they renewed their vows.
 * Richard Pryor remarried both Flynn Belaine and Jennifer Lee, staying with Lee the second time until his death.
 * After they got divorced, Joe Di Maggio started seeing Marilyn Monroe again, and was about to ask her to marry him again, but she died before that could happen.
 * Subverted with Elizabeth Taylor and Richard Burton. They got divorced, they remarried, then they got divorced again, for good.
 * John and Alicia Nash.
 * Pink and Carey Hart separated for several months, but never finalized the divorce and eventually got back together and now have a daughter.
 * Natalie Wood and Robert Wagner.