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->''There's no reason why Christine wouldn't be happier with Raoul than she would with the Phantom; he's closer to her in age, they've known each other longer, he's sincere, utterly devoted to her, and not '''psychotic'''; so [[Creator/AndrewLloydWebber Lloyd Webber]] and his cronies randomly turn him into a bitter, neglectful drunk with gambling problems, in order to smooth over the fact that they're trying to push Christine onto a guy '''who tends to strangle people when he gets upset.'''''
-->-- WebVideo/MusicalHell's Diva describing ''Theatre/LoveNeverDies''

When the author supports a relationship or resolves a LoveTriangle by [[CharacterDerailment turning the hero's romantic rivals into complete]] {{jerkass}}es.

Let's visit our old friends Alice and Bob. Alice loved Bob, but Bob didn't or couldn't return her love, so she left him. Now she's taken up with [[RomanticFalseLead Charlie]]. Charlie is [[NiceGuy sensitive]], {{rich|SuitorPoorSuitor}}, smart, and gives her everything she wanted from her relationship with Bob -- and ''then some''. She's madly in love and everything is perfect. Meanwhile, [[GreenEyedEpiphany Bob realizes what he had when Alice loved him]] and now he wants her back -- if he can win her heart before she marries Charlie and all hope is lost.

There's only one problem: [[WhyWouldAnyoneTakeHimBack Alice has no reason to take him back]]. She's met her perfect match, she's in love and life is bliss. And why should she believe that Bob, after not-loving her for so long, is genuinely in love with her now? She's over Bob. He had his chance, he blew it, and now everything is about Alice and Charlie.

Fortunately for Bob, the writer (call her Dee) is in his corner. Bob's predicament leaves Dee with her own set of problems. She needs to break up the happy couple so Bob can have Alice, but unlike most {{Romantic False Lead}}s, Charlie has no built-in SelfDestructMechanism that would take him out of the story. Nor can Dee just let Alice marry Charlie and leave Bob out in the cold. That wouldn't be [[StrictlyFormula formulaic!]] More seriously, that kind of GenreShift from RomanticComedy to pure {{Drama|Tropes}} may not please the viewers, since it punishes Bob even after he'd seen the error of his ways. And while Dee might want to [[CleaningUpRomanticLooseEnds make a happy ending for all]] or merely PairTheSpares, that means spending time developing a fourth character to be the replacement love interest of whichever man does not get Alice.

So Dee solves the problem by diverting viewer sympathy away from Charlie. Typically this is done by turning him into an utter {{jerkass}}. Alice's sweet suitor starts showing traits that were never there before. He gets [[CrazyJealousGuy jealous]] or [[DomesticAbuse violent]]. He reveals (or Alice discovers) [[BitchInSheepsClothing that he's cheating on her and has been for some time]]. Rarely is this even {{foreshadow|ing}}ed before it all breaks loose. It's a very fast CharacterDerailment which serves only to cut off the audience's investment in Alice/Charlie and drive Alice into Bob's arms.

If done too abruptly and without foreshadowing, viewers will feel that the writer has used an AssPull or DeusExMachina in order to get the OfficialCouple together. It doesn't look good for Alice, either: if Charlie's new InformedFlaw is small in comparison to Bob's, she looks petty, flighty, or indecisive [[MinorFlawMajorBreakup to dump him for it]]; if his flaw is enormous, she seems like a HorribleJudgeOfCharacter for not noticing it sooner.

(Even though we have been discussing this trope with [[AliceAndBob Alice, Bob and Charlie]], the three players can be any combination of genders.)

A subtrope of CleaningUpRomanticLooseEnds; cousin to DisposableFiance, FirstFatherWins and RomanticFalseLead, and of PanderingToTheBase when done to set up the FanPreferredCouple. Compare MinorFlawMajorBreakup, WhyWouldAnyoneTakeHimBack, and JumpingOffTheSlipperySlope. See also RelationshipWritingFumble and StrangledByTheRedString. DieForOurShip is when this is done in fan works. If one of the feuding romancers is a friend, then it's FriendVersusLover.



[[folder:Anime and Manga]]
* In the shoujo manga ''Manga/AkumaDeSourou'', NiceGuy Kamijou Yuucihi's character becomes derailed when he suddenly becomes a bit forceful towards Kayano. This doesn't really match his original character, and was obviously done so that Kayano's decision to go with [[{{Jerkass}} Takeru]] is justified. The saddest part is that, even when he turns more aggressive, he's still a ''much'' nicer guy than Takeru.
* ''Manga/DragonBallZ'' has Trunks, the KidFromTheFuture of Bulma and Vegeta, two characters who had no interaction up to that point, claim out of nowhere that Yamcha, Bulma's boyfriend since the beginning mistreated Bulma and was seeing other women. This makes little sense as Yamcha is portrayed in the series as a NiceGuy who wanted to get married and was a gynophobic character who had issues with other women. TheUnfairSex is also heavily added to the mix as Bulma was constantly openly chasing other men throughout their entire relationship, yet Yamcha being derailed into being unfaithful is supposed to make him look bad. The Japanese voice actors [[http://www.kanzenshuu.com/translations/supplemental-daizenshuu-super-voice-talks/ even pointed out]] how little sense Yamcha's handling made, as did [[https://www.youtube.com/watch?v=qJbGKHEjEw4 fans]]. A popular fan justification for Yamcha's sudden OutOfCharacter moment is Bulma made it all up.
* In the shoujo manga ''Manga/SteppingOnRoses'' (''Hadashi de Bara wo Fume''), Nozomu was originally a sweet gentleman who had been the merciful one that donated money to Sumi when her kid sister got really sick. However, in order to justify that Sumi should stay with Souichirou, his character becomes derailed as he suddenly becomes possessive and eventually an out-and-out {{Yandere}} for her. As if to make everyone no longer have any doubt who Sumi should end up with, he eventually goes so far as to try to [[spoiler:rape her, only to decide to commit a double suicide with her when the place gets set on fire]].
* Creator/KunihikoIkuhara has been accused of having done this in the ''Anime/SailorMoon'' anime. Since he's an open YuriFan and has said that he doesn't like the character of Usagi's boyfriend Mamoru, many fans have accused him of deliberately reducing Mamoru's powers and importance to the plot so Usagi would look better with other female characters. He cheerfully admitted to repeatedly [[MurderTheHypotenuse killing off]] Mamoru for this purpose, but of course the [[ExecutiveMeddling producers]] would always mandate that Mamoru be [[DeathIsCheap brought back]], much to Ikuhara's irritation. Then again this ''is'' [[TrollingCreator Ikuhara]] we're talking about, so who knows if he ''is'' really serious.
* ''Anime/XamdLostMemories'' falls into this trap a little with its treatment of Furuichi: although his bad behavior toward Haru ''is'' foreshadowed fairly early on in the story, and ''does'' follow fairly believably from what we already know about him, it's still pretty jarring to see him get stripped of virtually ''all'' his redeeming qualities in the last couple of scenes he's in to prove he's not good enough for her. Doubly so because Akiyuki, who is Haru's official love interest, actually ''caused,'' albeit unintentionally, much of Furuichi's current torments, yet never faces any punishment for doing so or even acknowledges that he might have done wrong by him.

[[folder:Comic Books]]
* Chuck Austen ''loooooves'' this trope.
** The Polaris/Havok/Nurse Annie triangle during his run on ''Uncanny ComicBook/XMen''. While Lorna has never been the most stable of people, Austen [[CharacterExaggeration blew her mental issues]] into [[{{Yandere}} full-blown bitchy psychosis]] to justify getting Havok together with the nurse he telepathically dated while in a coma (caused by her telepath son, Carter, who wanted a daddy and wasn't above committing MindRape to force Havok to be his daddy). This ended with [[RunawayFiance Havok dumping Polaris at the altar]] for [[RelationshipSue Annie]], and Polaris [[AxCrazy flipping her shit and attempting to kill them both]] before Juggernaut knocked her out. Polaris was put into psychic therapy with Professor Xavier; Havok and Annie ran off to Paris together, seemingly supported by ''all'' the other X-Men. Austen wasn't at all shy about telling people that [[AuthorAvatar Annie was a stand-in directly modeled off his own wife and that he envisioned himself as Havok]]; this did nothing to help fans accept the pairing... especially since, after all this, Annie was throwing herself at Iceman ''while still with Havok''! It's no wonder that Austen, upon leaving the book, put Annie [[PutOnABus on a bus out of town with Carter]] to protect his much reviled character from future reprisals. Though Austen did have her last issue feature a nebulous scene where it's implied that Carter has hooked up with Elias Bogan, a disembodied telepath who liked to trick kids into selling their parents to him to use as slaves to rape and torture for his own sick amusement...
** Exhibit B is his run on ''ComicBook/TheAvengers'', in which he pulled his trademark three-way CharacterDerailment on [[Comicbook/AntMan Giant-Man,]] ComicBook/TheWasp, and ComicBook/{{Hawkeye}}. Giant-Man became a full-on misogynistic {{Jerkass}} in the vein of his ComicBook/UltimateMarvel counterpart; Wasp became a ShrinkingViolet DomesticAbuse victim (oh, yeah, the [[NeverLiveItDown/ComicBooks Infamous Hitting Incident]] was brought back ''yet again'' for this just to cover all the bases, even though it had been supposedly ''finally'' laid to rest about three issues prior, during the Creator/GeoffJohns run); and Hawkeye was derailed into secretly having had a thing for Wasp and hated Giant-Man since the Eighties. All of this was promptly {{re|tcon}}versed by [[Creator/BrianMichaelBendis the next writer]] on the book, who killed Hawkeye and [[{{Chickification}} reverted Wasp back to her Sixties self]] before breaking her and Giant-Man up for good (or at least until someone else comes along).
** As proof that no company is safe, Exhibit C is his short career with DC. After being handed the reins to the ''Franchise/{{Superman}}'' book, Austen proceeded to make it clear that he hated Comicbook/LoisLane's guts (especially in interviews), hated the Superman marriage, and preferred Comicbook/LanaLang as Supes's one and only. His reasoning was that Lois was a [[GoldDigger gold digging bitch who only married Clark because he's Superman]] (even though she agreed to marry Clark Kent, not Superman) and tried his best to make readers agree with him. Since his "best" involved things like derailing poor Lois into a huge shrew who didn't give a damn about her husband, and having Martha "Ma" Kent expressly make the point that she would have rather had Lana as her daughter-in-law, this went over like a lead balloon and ended with Austen being fired. Readers also rejected such retcons as Lana's reasoning for naming her son with Pete "Clark" (rather than it coming from respect for an old friend, Lana had picked the name because she was still hopelessly in love), seeing them as desperate and creepy rather than sympathetic. As with almost every other relationship Austen ever wrote, later writers either ignored or outright rejected his take on things.
* ''Franchise/SpiderMan''
** Something similar happened to Black Cat in the comics. For publicity reasons it was decided to have Spider-Man marry at the same time in [[ComicStrip/SpiderMan the newspaper strip]] and [[Comicbook/SpiderMan the comic book]]; unfortunately at the time Peter was dating Felicia Hardy/Black Cat. The solution? Make Felicia go from morally ambiguous cat-burglar to the ally of an assassin for hire. Though the storyline was badly written and not helped by various production delays, this was no derailment. Peter and Felicia had broken up in 1984, about two years before the decision to have him and Mary Jane marry was taken. When the Black Cat started dating Spider-Man again -- in ''Spectacular Spider-Man'' #123 (published a mere five months before Peter proposed to Mary Jane in ''Amazing Spider-Man'' #290), she was in cahoots with the [[KarmaHoudini Foreigner]], the assassin responsible for the murder of Ned Leeds (a.k.a. "The Hobgoblin"). It also was clear from the start that she was motivated by a desire for revenge against Peter for getting ComicBook/DoctorStrange to remove the bad-luck power she had bought from ComicBook/TheKingpin. And this period of dating began with the Black Cat faking a bomb attack on her own apartment to get a pretext to invite herself in as Peter's new flatmate. Felicia is actually a victim of this repeatedly in the comics. The 1984 breakup was due to editors refusing to let Spider-Man have a longterm love interest at the time. As a result, despite showcasing that she would love Peter regardless, her attitude quickly derailed when the big moment came where he finally revealed who he really was to her. Now she refused to accept his Peter Parker identity and only loved him for being Spider-Man, repeatedly risked his identity going public over petty reasons, and constantly harping on Peter whenever he lied or kept a secret from her [[{{Hypocrite}} despite constantly lying about her own aforementioned Kingpin deal]], ultimately turning into a fullblown selfish whiny brat. After Peter and Mary Jane were married, she was reintroduced and turned into a crazy {{Yandere}} who even physically threatened Mary Jane. After this period she finally went through some much needed fixing, and for a good period of time her character went back to the way she originally was. Then ComicBook/SuperiorSpiderMan happened, having her be arrested by the new Spider-Man and subsequently become a crime boss after getting out of prison, outright ignoring the fact that she was not wronged by Peter himself.
** This happens to a few characters during the ''ComicBook/BrandNewDay'' run. Thanks to having a rotation of writers, each writer seemed to have their own {{O|neTruePairing}}TP. Carlie Cooper however was the intended love interest, so that led to the derailing of several characters to make room for her. Michelle Gonzales, Pete's {{Tsundere}} roommate, suddenly became verbally and violently abusive towards him, and Mary Jane, despite still apparently being deeply in love with him, becomes more distant and even turns into a ShipperOnDeck for him and Carlie. Bizarrely, even Black Cat, who was still in love with Peter even when she knew he was HappilyMarried to Mary Jane, became an approver of the Peter/Carlie relationship, ''despite never having met her''. However, once Dan Slott took over full time as writer, it took him less than a year to sink the Peter/Carlie relationship and brought Peter and Mary Jane much closer together as friends again.
** Happened during the 90's Howard Mackie/ John Byrne relaunch, where Mary Jane became more bitter and angry at Peter for being Spider-Man, to the point where she left him for a long period of time. Then she was blown up in a plane (she got better). All of this was done to get Peter single again, so he could start dating other characters, most notably Jill Stacy (Gwen Stacy's cousin.)
** The aftermath of the ''ComicBook/SuperiorSpiderMan'' run? MJ and Carlie pulling a ScrewThisImOuttaHere and leaving New York because they're fed up of being potential victims to anybody who has a grudge with Spider-Man (and MJ starts to date a fire-fighter, who is pretty much Peter without the powers, though she does see Peter yet again in the "Who Am I" mini-series which her influence restores an amnesia-ridden Peter's memories and he saves her life), and Black Cat pulling a WomanScorned FaceHeelTurn and wanting to destroy Spider-Man (and become the next Kingpin) because Otto destroyed her life and now she is not going to take Peter's apology unless she pries it from his dead body (and considering one of the first things she does is ''send Electro to kill Spider-Man'', she is either teetering close to the MoralEventHorizon or has passed it but it's imperceptible). All to promote [[CreatorsPet Silk]] as Spider-Man's new love interest.
* ''ComicBook/StrangersInParadise'': It was certainly ''very convenient'' that Francine's husband turned out to be having an affair near the end of the series, thus freeing her up to [[WillTheyOrWontThey finally]] get together with Katchoo.
* Devin Grayson was a comic book writer who got to be in charge of the late '90s [[ComicBook/TeenTitans Titans]] run. So far, so good. There's a problem, though... her OTP was Barbara/Dick, but some writers preferred him with Koriand'r. What was Devin's solution? [[DieForOurShip/ComicBooks Bash the SHIT out of Kory by making her an absolute bitch to Dick, so he can run back into Babs's arms.]] Dick and Kory had been long broken up since the end of Wolfman's run, but Grayson's character derailment simply made things worse, especially since the two agreed that they could simply be very good friends at the end of ''The Technis Imperative'' (a mini-series co-plotted by Grayson and Phil Jimenez that led to her run).
** Further complicated by the fact that when Grayson was writing Nightwing's series, she'd clearly intended for him to propose to Barbara when she wrapped up her run. However, at the same time in Judd Winick's ''Outsiders'', he portrayed Dick as having had a one-night stand with Kory to rekindle their relationship. The lack of communication between editorial departments further agitated fans of both pairing options, and had the result of turning Dick Grayson into a two-timer (which the character's reputation [[NeverLiveItDown couldn't quite recover from for a while]]). Other writers like Chuck Dixon had also previously attempted to downplay Dick's past relationship with Kory as simply an ill-advised fling.
** A later Nightwing annual by Marc Andreyko further made the love triangle look worse, when it was retconned in that Dick had slept with Barbara ''the night before'' he was due to marry Kory. It was also revealed that in an earlier point of their relationship, Babs went to deliver him flowers but instead bumped into Kory (who he'd just had sex with as his "first time"). These revelations were meant to explain why the engagement plot point became nullified in the "One Year Later" timeskip. Instead, it just complicated the issue and only gave fans further impression that Dick was an unreliable and indecisive cheater.
** What many writers don't seem to realize is that prior to the 90's, Dick and Barbara had never been a couple. This was mainly due to the fact that when he was Robin, Dick was still a teenager and Barbara was portrayed as in her mid-20's at least (she'd been in the US Congress). Dick had been pretty much eased out of the main Batman titles and eventually was with the Titans full time. Becoming Nightwing was done so he'd no longer be under the control of the Batman editors.
* Some writers at DC seem to '''adore''' Franchise/{{Superman}}[=/=]Franchise/WonderWoman, as evidenced by the fact that many different {{Elseworld}}s either derail Lois Lane to get rid of the marriage, or simply [[MurderTheHypotenuse kill her off entirely]]. A stand-out example is ''ComicBook/JLAActOfGod'', where a mysterious event de-powers every non-technological superbeing on the planet and made all magically powered heroes disappear, after which Lois breaks up with Clark ''because'' he lost his powers. Granted, the fact that Clark is busy being [[{{Wangst}} Angsty McWhineNCry]] about the whole thing really didn't help matters, but still. And of course, Wonder Woman, despite being, you know, ''magically powered'', is still around for Clark to lean on. And now, thanks to the Comicbook/{{New 52}} reboot, Clark and Lois have ''never'' been married, thus allowing DC to ''finally'' hook Superman and Wonder Woman together. Of course, this is lampshaded in the final issue of ''Comicbook/JusticeLeagueInternational'' when a time travelling Comicbook/BoosterGold attempts to warn what's left of the team of something in the future, only to be interrupted by the two's first kiss and gawking in utter shock.
** Poor Billy Batson also gets this treatment in ''ComicBook/SupermanDistantFires'', where he goes from a boy scout on par with Superman to a megalomaniac who [[spoiler: kills Diana when she refuses to get back together with him]] and wants to take over the world.
* The infamous bitchslap that sent [[Comicbook/ArchieComicsSonicTheHedgehog Sally Acorn]] into JerkSue territory has shades of this; after being a romantically entangled for many years, a supposed mandate came down ordering Sonic to not be in a permanent relationship, and the next thing readers knew, Sally was bitching out Sonic for not ditching his duties to be her consort, which led to him getting into a torrid LoveTriangle with Mina Mongoose and Fiona Fox. However, after a change of writers the love triangle was dissolved and Sally was made Sonic's one-and-only canonical love interest (at least, until the ContinuityReboot happened).
* Similar to Chuck Austin, Creator/GrantMorrison went this way with his ''X-Men'' run. Creator/JoeQuesada wanted to break up Comicbook/{{Cyclops}} and Jean, so he told Grant to kill her off. Perfectly normal in a super hero comic, but instead of just letting her die in a good, heroic way or even stuffing her in a fridge like most writers do, he decided the best way was to derail Jean, Scott, and Emma Frost in order to make a 'love triangle' before killing off Jean so Scott can get together with Emma. To do so, he had Cyke, currently in a dark place following his merge with Apocalypse, seek therapy to deal with his issues, which Emma provides with her previously-never-mentioned PHD in psychology. Then, she has psychic mind sex with him to let him live out his deepest sexual fantasies that Jean would never do so, while projecting the image of Jean. Jean at first is rightfully pissed at the two, especially Emma, but she receives no punishment since she 'did it out of love' for Scott, despite the fact the [[StrangledByTheRedString two had never previously had much interaction beyond the psychic sex]], and ''Jean'' is called out for having no sympathy for her. So, Jean forgives them all, only to be killed by Magneto despite being the Phoenix (and as such, immortal) at the timewith Jean then pushing Scott beyond the grave to move on. So in short, who was supposed to be 'in the right' was emotionally manipulating a man and is rewarded with becoming the second in command, the ''real'' victim of the situation is made out to be a boring and dull prude, and the man in the middle is essentially mind raped when he needed therapy (which he never got, possibly explaining his own latent CharacterDerailment) and ends up looking like a tool and a douche.

[[folder:Films -- Animation]]
* Subverted in ''WesternAnimation/TheLEGOMovie''. Batman is clearly set up as a RomanticFalseLead character, culminating in a scene where he seemingly announces ScrewThisImOutOfHere in the middle of a crisis, running off to the Millennium Falcon to hang out with Han Solo (and insisting to his girlfriend that part of his relationship is being able to ditch her and party whenever he wants). His girlfriend is furious, TheHero proposes that she stop going out with him because he's a jerk and doesn't respect her... and Batman reappears, having stolen a vital component from the Millennium Falcon that he needs to solve their crisis.

[[folder:Films -- Live-Action]]
* In ''Film/{{Carefree}}'' (1938), [[TriangRelations Stephen loves Amanda, who loves Tony]]. Any sympathy the audience may have for Stephen will likely disappear once he tries to marry Amanda while she's [[{{brainwashed}} hypnotized]] into thinking she loves him and gets a restraining order to keep Tony from undoing the brainwashing.
* Deconstructed in ''Film/MyBestFriendsWedding''; Julianne ''does not'' marry her best friend, and when she tries to break him up with his sort-of [[ManChild Woman Child]] girlfriend so she can get the guy for herself... ''she'' comes off as utterly clingy and unsympathetic. [[MustMakeAmends And she's the one who has to clean up all the mess she caused]].
* ''Film/SkyHigh2005'' is an interesting example of this trope. The fact that Gwen starts to act more like the AlphaBitch as the movie goes on is probably meant not just to make Will's [[ChildhoodFriendRomance best friend Layla]] seem more appealing, but also to hint that [[spoiler:Gwen is the BigBad]]. That said, Gwen acting bitchy to [[AllOfTheOtherReindeer the sidekicks]] or acting jealous of Layla doesn't really make sense for her true motive ''or'' the preppy NiceGirl facade that she's putting on, so it still kind of comes off as random and forced.
* Deconstructed in ''Film/YoungAdult''. The main character Mavis (a whiny [[ManChild Girl-Child]] is convinced that she can seduce her ex-boyfriend to be with her again, despite the fact that he has a new kid. It turns out [[spoiler: his wife feels sorry for Mavis and leaving her never entered her ex's mind.]]
* ''Film/RunFatBoyRun'': a guy enters the London marathon to win his ex back, who has a new guy already. New guy went from friendly [[TheAce Ace]] to a child-hating ControlFreak. Granted, there were some early hints to his inner bastard - his competitive streak, apparent [[ChildHater annoyance at children]], and... he's ''[[EagleLand American!]]''
* Subverted in ''Once Upon a Time in the Midlands''; events seem to be going this way, with Dek (the new, sweet, rather hapless love interest) kicked out of the house and Shirley letting Jimmy (bad-boy ex and father of her daughter) move in and starting to fall back into a relationship with him. The subversion being that Jimmy is then revealed to ''genuinely'' be a dick who hasn't changed in the least, and Shirley does in fact get back together with Dek in the end.
* In ''Film/HarryPotterAndTheHalfBloodPrince'', Ron's girlfriend doesn't do or say anything negative toward anyone until the very ''scene'' she and Ron break up. In [[Literature/HarryPotterAndTheHalfBloodPrince the book]], Lavender was a ''lot'' more clingy and annoying, to the point at which Ron pretended to be asleep so he wouldn't have to deal with her, leading her to start annoying Harry for a third party's views on their relationship. Of course, the real reason Ron was with her was because she was pretty and liked him; before they hook up, it's Hermione he's crushing on, not Lavender.
* Used with Johann in ''Film/TheHottieAndTheNottie''. Johann is introduced defending June from humiliation, and is a dentist, enabling him to clean up her crooked, ugly teeth. He's also a former Marine, a Harvard graduate, a great guitar player, a male model, a pilot, and other things that make him absurdly perfect, and much better than loser protagonist Nate. But when June eventually becomes beautiful and starts going out with him, he turns out to be more or less a self-involved jerk. However, the extent of his jerktitude is a couple of selfish comments that offend Nate and June.
* ''WomanOnTop'' falls on the "informed flaw" side of things. The ex-husband is truly sorry about cheating on her, but they needed to get rid of her new love interest. They get in a fight when he (under orders from the producers) attempts to [[ExecutiveMeddling change elements on her show]]. She dumps him over this single fight, which isn't even his idea, and goes back to the man who cheated on her just because he wasn't able to be on top while they had sex.
* In ''Film/KickAss2'', Dave's girlfriend Katie, having been thoroughly established as a genuine NiceGirl in the first film, is suddenly derailed into a jerk that has been cheating on him, right before she dumps him. It's possible that having Katie Dave's girlfriend in the movie wouldn't have meshed with the story in the comic where they never were together (in fact, she was already seeing someone and when Dave learned all of this from her, her beau punched him in the face). This is to facilitate his romance with Hit-Girl.
* Similarly, in ''Film/TheInbetweeners2'', Lucy changes from a NiceGirl who Simon got into a relationship with at the end of the previous film to a {{Yandere}} who deletes friends from his Facebook account, destroys his possessions [[spoiler: and is cheating on him with Pete.]]

* Gatsby is trying to invoke this in ''Literature/TheGreatGatsby'' with Daisy by getting her away from Tom. Unfortunately, [[spoiler: all Gatsby gets is to be the other guy in an affair, and ends up dead when Tom's mistress is killed, and her husband murders Gatsby thinking he killed her, and Daisy and Tom stay together, despite their shallow marriage.]]
* This happened in ''Literature/{{Twilight}}''. When Edward leaves in ''New Moon'', Bella gets close to Jacob, who falls in love with her. When Edward comes back, in order to justify Bella staying with him rather than Jacob, the author has to make Jacob do some kind of drastic, out-of-character things, like forcing Bella to kiss him, and threatening suicide to manipulate her. Then again, Bella already chose Edward as soon as he came back, before Jacob started to behave badly, so it's more of a "justifying her decision not to change her mind and go with the guy who treats her like an equal and actually seems to have any feelings for her besides claiming that he loves her" than a "justifying her decision to go back."
** Of course, given how Edward behaves in the relationship, one could just as easily assume that Meyer was trying to make Jacob ''better'' as love interest material, especially since Bella only realizes she loves him ''after'' the forced kiss and all.
*** This has been confirmed by [[WordOfGod Stephenie Meyer]] - the changes in Jacob's characterization was meant to make him a serious contender for Bella.
* Jonathan's behavior in the third book in ''Literature/SongOfTheLioness'' series qualifies in spirit, if not all specifics. Up to that point, he'd been portrayed as a good, upright guy. He certainly was, in the second book, a bit focused on a girl, but charming enough for Alanna to be very in love with him. Then he TookALevelInJerkass in the third book and starts [[EntitledToHaveYou acting like marrying Alanna is a done deal]] and flipping out when she wants time to think. Then in the span of one chapter he is that and more, all to push Alanna into the arms of the lovable rogue George and later Liam. Pierce had originally intended Jon and Alanna to be the OfficialCouple, but it was while writing the third book that she came to believe they didn't work together -- and if Jon does come across as cruder, some of the seeds for his behavior ''were'' glimpsed in the previous book, it was just played out in a more romantic light. Because Jonathan believed they were "fated" to be together, he took her assent to things as all but a given, which was exactly what infuriated her later on when the things in question were marriage and family instead of sex.
* While Cho's behavior in ''Literature/HarryPotterAndTheOrderOfThePhoenix'' is [[JustifiedTrope justified]] since she is in mourning and not really ready for another relationship after [[spoiler: Cedric's murder]], she becomes a ClingyJealousGirl after hooking up with Harry. They don't last that long but do become AmicableExes.
* ''Literature/TheHouseOfNight'':
** Erik from is pretty much the perfect boyfriend to Zoey for the first three books. Then he suddenly turns out to be a possessive jerk in later books, thus justifying Zoey's displays of interest in other boys. Though considering that Zoey wasn't exactly a faithful girlfriend to him, his new attitude toward her might be somewhat justified. In addition, he exhibited a surprisingly cold, condescending, and sometimes insulting behavior towards his ex-girlfriend Aphrodite, which everyone overlooked, because they saw her as a borderline DirtyCoward AlphaBitch with SkewedPriorities (instead of TheWoobie ManipulativeBastard BrokenBird being a practitioner of BrutalHonesty).
** [[ZigZaggingTrope Zig-zagged]] with Heath, he starts a drunk-jock-ex-boyfriend in ''Marked'' who looks in danger of being written off for good a number of times. He stays in the story almost completely by one virtue: the fact that he's taking advantage of Zoey's low self-control over her new bloodlust to essentially roofie-rape her every time she sees him by cutting himself and triggering her compulsion to drink: an action that's both intensely arousing, energizing, and creates a mystical bond between them against her control. Then of course she realizes he's her soul-mate (one of them anyway) after he almost gets himself killed trying to win her back again, and all that is swept under the rug. He is then [[spoiler:killed off]] in ''Tempted'', but then [[spoiler:is reincarnated by Nyx to be Neferet's Vessel, named Aurox.]] However, [[spoiler:Aurox retains some of his free will and is eventually able to choose the side of Light, thanks to his soul connection with Zoey]], so we don't know what to expect.
* Perhaps the swiftest use of this trope is used in Literature/TheRomanMysteries. Throughout ''The Scribes of Alexandria'' Nubia spends months travelling to a Nubian settlement in the hopes that she'll find her own people there. She is eventually reunited with her betrothed, only to be torn between marrying him or returning to Rome with her friends. It's a tough decision, but luckily her betrothed goes from a nice guy to a potential wife-beater within the space of a paragraph.
* ''Literature/SweetValleyHigh'' and its spin-offs pulled this several times, usually to have the girls dump a one-shot love interest and return to their regular boyfriends, because StatusQuoIsGod.
** This is actually averted when Todd Wilkins returns to town only to find Elizabeth happily dating Jeffrey French. Even though by the book's end Elizabeth does dump Jeffrey for Todd and Jeffrey is left hurt and angry, at no time does he ever turn into a psycho. He even manages to pull an IWantMyBelovedToBeHappy in the midst of all his grief.
* Literature/SisterhoodSeries by Creator/FernMichaels: As the series goes on, Isabelle Flanders forms a relationship with Stu Franklin, and Annie de Silva forms one with Little Fish. By the book ''Cross Roads'', Stu and Fish end up suffering ''huge'' CharacterDerailment! Both men start treating their girlfriends like prisoners, neglecting them, turn out to be cold-blooded murderers, and also show a huge amount of HoYay for their boss Henry "Hank" Jellicoe. ''Deja Vu'' tries to justify it by saying that people only let others see the best of them most of the time.
* Gale Hawthorne might be one in ''TheHungerGames''. His personality is the same in the third book, but his beliefs get more pronounced, he clashes more often with Katniss, and he ends up inadvertantly [[spoiler:killing Primrose by having designed the trap that Coin deployed, which took Prim's life]]. [[WordOfGod Suzanne Collins]] has never made it a secret that Gale was not supposed to be a love interest, and was in fact Katniss' cousin in the original version of the books, but [[ExecutiveMeddling the publishers demanded a love triangle in the wake of Twilight]]. Whether this makes it more likely that Gale was deliberately derailed or not is up for debate.

[[folder:Live-Action TV]]
* One is in the US version of ''Series/QueerAsFolk'', where Justin leaves Brian for a much more romantic guy, who suddenly has an affair.
* ''Series/SexAndTheCity's'' Alexandr is one of the best examples of this trope, going from an amazing, sweet, and sensitive guy to a jerk who ignores Carrie and proves to be completely self-absorbed before leaving for Paris.
* Charlie in ''Series/UglyBetty'' went from sweet, likeable girl to jealous, two-timing harpy in no time. Then again, the show ''is'' partly a soap parody...
* Out of the blue, Tess on ''Series/{{Roswell}}'' was revealed to have been repeatedly brainwashing their friend and conspiring with their enemies so they could break up her and Max.
* Played straight in the BBC's ''Series/RobinHood''. Robin starts a relationship with Isabella, a seemingly intelligent, rational, and compassionate woman. However, halfway through the series, Isabella throws an inexplicable [[CharacterDerailment temper tantrum]], [[LoveMakesYouCrazy goes insane]] and [[LoveMakesYouEvil tries to kill him]] after Robin tells her that his mission must come before her. This is apparently done so that the writers can kick-start Robin's love story with Kate. Oh, and if you're wondering where Maid Marian is during all of this, [[spoiler:she was murdered by Isabella's brother last season]]. Even more irritating was the fact that Robin cites his commitment to England and his inability to have a normal life as the reasons for breaking up with Isabella. Yet he hooks up with Kate two episodes later, [[AesopAmnesia having completely forgotten his own reasons why it's not a good idea to be in a relationship]].
* ''Series/{{Friends}}'' has a few examples:
** After Chandler moves in with Monica, Joey's new roommate is a woman; he's attracted to her and they eventually get together. Then, she inexplicably turns out to be unable to stand Chandler and Monica, which leads to Joey breaking things off and the woman moving out.
** Paolo, Rachel's boyfriend in Season 1, is introduced as a dumb, but harmless guy who enjoys being with Rachel... until he randomly becomes a JerkAss who tries to cheat on her. This was to make way for the Ross/Rachel relationship.
** Repeated ''nine seasons later'' with Charlie, Ross's girlfiend. She seems pleasant, intellectual, and well-matched with him. Out of the blue she cheats on Ross with her ex-boyfriend right in front of him. And yep, this was to accommodate ''another'' Ross/Rachel hook up for the end of the series.
** Kathy, Joey and then Chandler's girlfriend in Season 4, is a very strange case. Although she does kiss Chandler while still with Joey, it was portrayed sympathetically as they'd genuinely fallen in love, while she and Joey are very casual. She eventually breaks up with Joey on good terms and enters into a proper relationship with Chandler, until eventually ''Chandler himself'' is the one who gets derailed. He sees her acting out a simulated sex scene with another guy in a play, and immediately assumes she much be having an affair with him. She denies this, but Chandler accuses her in such an immature and harsh way that [[SelfFulfillingProphecy she DOES end up having an affair with the guy.]] This a major wake-up call for Chandler and a turning point for his character as far as relationships were concerned, as he is notably a lot more mature with his next girlfriend (Monica) and they eventually end up HappilyMarried.
** Gary, Phoebe's cop boyfriend in season 5 was built up over several episodes as a nice, sweet person who Phoebe had genuinely fallen for. He rushed her into moving in with her, and she accepted even though she clearly wasn't ready. Instead of having them have a conversation about this and legitimately breaking up, their last scene together is them waking up together in their shared apartment and he shoots a crow through the window, completely out of the blue, for making too much noise.
** Barry, Rachel's fiancé from before the series. Initially he was a nice, but boring guy whom she left at the altar because she didn't love him. Later its revealed he was a SmugSnake cheated on with her best friend throughout their engagement.
** David, to some extent. During his sporadic appearances in the first nine seasons, he's shown to be a kind and compassionate person with a successful career and genuine affection for Phoebe. In his final appearance at the end of Season Nine, he's suddenly a pathetic loser who can't even afford to buy a legitimate diamond ring for Phoebe. At the end of the season, [[spoiler: Phoebe dumps him in the most callous and humiliating manner possible, and Mike becomes her love interest for the rest of the series.]]
** Specifically subverted when Richard returns in Season 6. When he asks Monica to leave Chandler for him, he's portrayed as the NiceGuy he's always been: charming, intelligent and, in Chandler's eyes at least, a much better prospect. The only problem is that Monica doesn't love him anymore, she loves Chandler, and there isn't anything he can do about it. This actually makes her decision to stay with Chandler much more heartwarming, as it becomes clear that she hasn't chosen him because she didn't have a better option - she's with him because he's the one she wants.
** Then there's Emily, another bump in the Ross/Rachel road. They have a season long courtship. Everyone, except the jealous Rachel, really likes her and they plan their wedding in England. After being humiliated when Ross says Rachel's name during their wedding vows and making the somewhat reasonable demand to not see Rachel anymore if he wants the marriage to work, suddenly everyone acts as if they never like her and she was being unfair.
* In ''Series/FamilyMatters'', Myra's ClingyJealousGirl behavior towards Steve is turned UpToEleven (Even after they break up) in the final season to the point where she installed a spy cam in his glasses so she could watch him through a monitor in her bedroom. This so Steve, who'd been happily in a relationship with Myra for years, could be paired with Laura (whom he'd had a completely unrequited crush on, played for comedy, for a good while, but by now, had ''long'' been dropped.)
* In ''Series/{{Home and Away}},'' this happens to Sam Tolhurst. At first she comes across as a sympathetic character, with a tragic backstory, (on the run from accomplices of her drug dealer husband) and is portrayed as a good match for Jack. Unfortunately, when they get engaged, and especially after getting married, she becomes a possessive controlling bitch, especially towards Jack's ex-wife Martha. At first this is justified (specifically when she walks in on Martha wearing her wedding dress), but the writers derail her during her exit storyline. She murders a criminal who had been blackmailing her to force her to hide him, after which we learn that she had lied about her backstory -- she was the ringleader in her husband's drug operation, and was on the run because she'd allowed him to take the fall. After she's exposed, she kills herself and almost succeeds in framing Jack and Martha. The worst part is that the writers left several details out of this retcon, (the fact that she'd tolerated Shane's drug dealing up until she'd witnessed him killing someone in cold blood, and the fact that he'd been doing it to raise money for their terminally ill daughter). While it would have been entirely plausible by this point to handwave these as Sam's lies to Jack, they are unmentioned in the letter which reveals the truth, and Jack himself doesn't bring them up when he confronts her about it.
** Dexter Walker's girlfriend Steph Green started out as a caring and likable nurse, who supported him when he found out his brother-in-law was dying, brought out his relaxed side and even had the maturity to take a step back when he began to push too hard to make his family accept their relationship and tell him he needed a friend rather than a girlfriend. Then someone seemed to realise she was coming across as a better match than his OneTruePairing with April Scott, so she abruptly became aggressive and controlling, pressuring him into having sex with her at work, then turned out to be neglecting her patients and making up results instead of doing the proper tests. She was promptly fired and reported Dexter's indiscretions with her as a parting shot.
* Juliet from ''Series/{{Lost}}'' decides her three-year relationship with Sawyer is over as soon as Kate returns. She is sure Kate is the one for him, heedless of Kate's or Sawyer's opinion on the matter. [[spoiler:In a subversion, they reunite in the afterlife while Kate is with Jack.]]
* Repeatedly done on ''Series/TheDrewCareyShow'' as part of the central character's general run of bad luck. Nicki, his FormerlyFat fiancée, left after realizing how much weight she'd put on while they were together. Working class WrenchWench Sharon seemed perfect for Drew, but it was later revealed that Drew was in fact the other man when they meet her real boyfriend at a ballgame. The intended endpoint was a long-term thing with Kate, who was ironically derailed herself when Christa Miller ditched the show for ''Series/{{Scrubs}}''.
** When Drew started taking night classes, he met an older woman, and they started dating. There's a lot of fun at their expense over the age difference, but they seem like a happy couple. But then in her last appearance, she begins mothering Drew (when previously she had treated him like an adult). He didn't mind at first, until he [[{{Squick}} saw his mom's face during sex]], at which point they both agreed to end it.
* ''Series/DawsonsCreek'' has a tendency to do this to Pacey's girlfriends whenever they want him to get close to Joey. Andie, who's set up in Season 2 as his {{Adorkable}} soul mate, the first person who believes in him and helps him turns his life around, abruptly cheats on him in between seasons, then hammers the point home by cheating at an exam and lying about nearly being raped. Audrey, who, in Season 5, is portrayed as the first girl to be Pacey's equal, suddenly turns from a lovable party girl into a screwed-up alcoholic who ends up in rehab the following season.
* Louis in ''Literature/GossipGirl'' has been steadily becoming less sympathetic over the course of Season 5, as Chuck becomes a better person. This is lampshaded by Blair, as well as explained by the fact that Louis is well aware that in a competition against Chuck he'll lose no matter how nice and sweet he is, prompting him to become more underhanded in his desperation to keep Blair.
** Dan becomes this to Blair when their romance arc is coming to an ending and it's time for them to return to being the halves of their respective [[OfficialCouple official couples]]. He cheats on her with Serena, blames the whole mess on Blair's feelings for Chuck (despite her having the decency not to sleep with the next guy before braking up with the former - unlike Dan) and [[TookALevelInJerkass takes a whole new level on jerkass]] after their break-up, going after all their friends by writing hateful pieces about them in press. He however still carries a torch for Blair, so decides to release a flattering chapter about Chuck in order to get back into her good graces... and only after he realizes he's lost all the chances with her, he releases a chapter about her - vicious, in turn. [[{{Hypocrite}} All this while claiming he's publishing it only for the sake of truth.]] It's quite funny where one remembers that the show started with Dan as the UnluckyEverydude moral compass of the cast and Blair as a monumental RichBitch.
** A very strange and brief derailment of Jenny occurs in Season 2, when she seems to be on the verge of getting together with Nate. Nate writes a letter to Jenny telling her his feelings but Vanessa steals it before Jenny can read it. Jenny, having worked out the general idea of what Vanessa's up to if not the specifics, is persuaded to get her own back and humiliates Vanessa by tricking her into going to a ball in a see-through dress. Despite knowing full well what Vanessa did, Nate abruptly dismisses Jenny, telling her she's not the girl he thought she was, and...gets together with Vanessa instead. When Jenny immediately defends Vanessa to the mean girls, it's [[WhatDoYouMeanItsNotHeinous hard to tell]] what Nate's problem is.
* In the episode "The Grinning Man" of ''Series/JonathanCreek'', Jonathan manages to land himself a pretty, intelligent and caring girlfriend who (despite a slightly ditzy interest in magazine quizzes), is refreshingly normal compared to many of Jonathan's other love interests and is understandably worried when he goes investigating murders. At the end of the episode she runs off with Joey's boyfriend despite having never met him, paving the way for a possible Jonathan/Joey relationship.
* ''Series/{{iCarly}}'' used this in an episode, to break up Jonah and Sam. They spent 60% of the episode being sickeningly sweet to each other. All of Sam's attention was being spent on him, and it was causing problems for her friendships with Carly and Freddie. Also impacting on their webshow. Instead of Sam coming to realize that she can't spend all her time with him, or have Jonah realize the same and back off slightly, he suddenly tries to cheat on Sam with Carly, making all the potential issues moot when they wedgie-bounce the sucker for trying to cheat. Which [[FridgeBrilliance actually made sense]] after "iKiss" with a bit of [[WildMassGuessing WMG]]. In "iKiss", which happened after she dated Jonah, Sam says that she's never kissed anyone, meaning that Sam must have never kissed Jonah. It's possible that Jonah got fed up with it and tried to kiss Carly instead.
* In ''Series/FreaksAndGeeks'', Sam is hopelessly smitten with cute [[AllGuysWantCheerleaders cheerleader]] Cindy Sanders. Toward the end of the show's first and only season, Cindy finally starts dating Sam, and they almost immediately learn that they have no common interests and don't have any fun together. The previously sweet-natured Cindy is also revealed to be (mildly) bitchy and manipulative, as well as a bit vapid and dull.
* ''Series/TheOfficeUS'':
** The series gave this treatment to Karen. After Pam revealed she called off her wedding because of Jim, Karen, having served a whole season as a likable match for him (sparking Team Karen and Team Pam factions in the fandom), the character was shown pushing Jim into promising to move to New York with her if either got promoted to the open corporate job there (explicitly stating that she wanted to get him away from a certain other person), and leaving to have lunch with friends while he had his interview. Others questioned how the show could arguably portray her as a villain for these actions but have Jim ''abandon her in New York'', after they drove up together, just so he could drive back home and ask Pam out right away (though he acknowledges his behavior in the season four premiere).
** Played infuriatingly straight with Andy and Erin, the former whom lost his job trying to get the latter back. One season later Andy leaves Erin behind to go on a 3 month boat trip conveniently leaving the new guy Pete to comfort her.
* Subverted in favor of the dramatic route on ''Series/{{Battlestar Galactica|2003}}'', where Kara and Anders' relationship stays intact despite Kara's affair with Lee (Kara and Lee having been the FanPreferredCouple in the previous season).
* A regular occurrence on ''Series/GilmoreGirls'':
** Dean's wife Lindsay became a shrill harpy who overworks her husband as Rory suddenly becomes interested in Dean again (although Lorelai called her out on this one). Ironically, Dean would get derailed himself for the actor's exit from the show.
** Jason threatens to sue Richard after he and Jason's father essentially destroy his livelihood, just in time for the Luke/Lorelai relationship to finally happen.
** Marty is at first a sweet classmate who takes an interest in Rory but she spurns his advances and he takes a long bus ride only to return as a huge Jerkass in the last season.
* Frequently used on {{Soap Opera}}s, in scenarios that play out almost exactly as in the page description. A formerly decent third character is almost inevitably destroyed in order to prop up either the show's designated SuperCouple, or whatever couple the writers wanted to pair up.
** A particularly good example is on ''Series/AsTheWorldTurns'', where Jack dumped the manipulative, scheming Carly to hook up with MarySue Julia. Fans clamored for a reunification of Jack and Carly, so within a year, Julia went from MarySue to {{Yandere}}, pulling increasingly horrific stunts that included attempted murder, kidnapping, and RAPE, giving Jack the perfect excuse to return to Carly--with whom he proceeded to have an on-again, off-again relationship that was just as unhealthy and destructive as their previous one (and included the sacrifice of even MORE examples of this trope for both of them) before finally marrying for good in the series finale.
** An almost identical example played out on ''Series/GuidingLight'' with Josh, Reva, and Annie.
** An interesting subversion on ''Series/GeneralHospital'', where rather than being an obstacle, the Derailing Love Interest was ''part'' of the FanPreferredCouple--the male half of the pairing was already in a happy relationship, and of course, it would make no sense for him to break up with a woman whom he adored. But rather than inexplicably ruining ''her'' character, the writers instead had him develop complete amnesia following an accident, leaving him with no memory of or regard for her, thus paving the way for his new relationship.
* Played straight in ''Series/{{Glee}}'': After [[OfficialCouple Rachel and Finn]]'s sort-of relationship hits a rut, she meets Jesse St. James, the lead singer of rival Glee club Vocal Adrenaline. Naturally he's her equal, understands her perfectly, etcetera. When he is very obviously TheMole, he admits that [[BecomingTheMask he's starting to have feelings for her]]. Right after ''that'' happens, of course, he becomes utterly cruel with the [[spoiler: egg-assault in the parking lot and him acting like she somehow did something to deserve it]], especially since the last time we saw them they were perfectly happy together and she had done nothing to upset him. It's clear he's only doing it because he wants to go back to Vocal Adrenaline so that he can win a fourth national show-choir championship, and needs to prove his loyalty to the team above all else. [[spoiler: But it may be subverted. TheBusCameBack with him on board, and he ends up apologizing to Rachel and is obviously still very much in love with her. However, she didn't care and got back with Finn]].
** Coach Beiste's husband is randomly revealed to be abusive. Granted, Dot-Marie Jones sold the storyline for everything she was worth and then some, but it came ''completely'' out of left field. TruthInTelevision, really -- people with abusive tendencies often take great pains to be nice and charming up until they can't hold it in anymore or feel the other person is trapped with them.
** Also with Quinn in Season 2. When Finn and Quinn got back together in Season 2, their relationship was very believable and well-received. However since the writers obviously wanted Finn and Rachel back together, they make Quinn controlling. (Of course Quinn has also been derailed when she wasn't a love interest).
* This was forced on Will Griggs on '' Series/{{Neighbours}}'', not because he was a RomanticFalseLead, but because the actor had left the show early and they chose to bring in a SuspiciouslySimilarSubstitute. At the time he was written out, Carmella was furious with Will for lying to her and hiding his real identity as Sebastian Barnes one of the richest men in the country, but he was still trying to get her to forgive him. Then suddenly he was gone, and his adoptive brother Oliver arrived to reveal that Sebastian's entire personality had been faked, and was based on Oliver. This led to Carmella and Oliver getting together, and apparently rendered insignificant Will's substantial number of good deeds, such as standing up to Paul's attempts at blackmail (his 2% share of Lassiters was enough to give Paul a controlling interest, and Paul used that to get Will's friend Ned fired); standing by Carmella when she was badly burned by her mentally unstable cousin, and thwarting an attempt by Janae's pervert of a boss to spike her orange juice. It got worse later in the year when Oliver's biological brother Declan was kidnapped, and Sebastian (offscreen) only agreed to pay the ransom if Oliver gave up his share in the Barnes hotel chain.
* Happened to Eddie [=LeBec=], Carla's husband, on ''Series/{{Cheers}}''. They foreshadowed it for a few episodes, but transformed him from the nicest guy you'd ever want to meet, to a cheater who married the woman he had his affair with and never told Carla (it became public at his funeral). This was deliberate payback on part of the producers for Jay Thomas having insulted Rhea Perlman's attractiveness on national radio.
* The writers of ''Series/{{Frasier}}'' saw this trope looming at them from a mile away and nipped it in the bud by never bothering to make Niles's RomanticFalseLead Mel Karnofski into a sympathetic character in the first place. From the very start she was both characterized and described as a slightly-kinder doppelganger of Niles's first wife [[TheGhost Maris]], a controlling, domineering, hysterical ManipulativeBastard and JerkAss extraordinaire (whom [[ShipperOnDeck all the characters despised]]), explaining Niles's attraction to her as a bad pattern (similar to how some women who leave an abusive boyfriend fall for men exactly like him over and over), instead of wasting time trying to make her into a person for whom Niles could fall for healthy reasons, but [[DieForOurShip the fans would inevitably vilify anyway.]]
* ''Series/{{Supernatural}}'' has an odd case of a love interest being derailed for reasons unrelated to their being a love interest. In season 4, Dean meets Anna Milton, a fallen angel whom he quickly takes a romantic attraction to. Originally, she was going to replace Castiel (who was going to be killed by Alistair) as Dean's angel guide, however this hit a snag when Castiel became the show's EnsembleDarkhorse, with both fans and critics responding more positively to him than any character other than the Winchesters themselves. Thus, Castiel was spared and his role in the series expanded. This had the unfortunate side effect of making Anna redundant, however, and she was given only a few more appearances before JumpingOffTheSlipperySlope and deciding she needed to erase Dean and his brother Sam from existence. Then again, for [[YaoiFangirl some people]], it ''is'' related to Anna being the [[HoYay wrong love interest]].
* ''Series/{{Smallville}}'' made a habit of this with Lana's love interests. Jason Teague was thrown into the TitleSequence in his very first appearance, only to get less and less screentime until, at the end of the season, [[spoiler:he was revealed as a member of some ridiculous secret society and then [[DroppedABridgeOnHim unceremoniously killed]]... by meteors.]] This was only one season after Lana's previous boyfriend, Adam, became increasingly unstable and villainous...[[spoiler: before dying of delayed liver failure while trying to shoot her.]] This seemed to happen with Whitney, her original boyfriend who was PutOnABus at the end of season one, when TheBusCameBack in season two and he immediately started being sinister and throwing Clark through doors, until it turned out that actually he [[spoiler:was dead; the villainous version was her [[VoluntaryShapeshifting shape-shifting]] StalkerWithACrush]].
* ''Series/{{Charmed}}'' derailed both lovers in the relationship at different times with Phoebe and Cole. The relationship went through a LOT of drama ([[spoiler:Cole became possessed by the Source of all evil, made Phoebe his queen and got her pregnant with a demonic baby which forced her to kill him]]). She ended season 4 still loving him but just afraid to use magic to resurrect him. Then the first episode of season 5 she suddenly blames him for everything that's gone wrong in her life and threatens to kill him over a bad dream she had. The writers then realised Cole was looking too sympathetic and abruptly made him go mad and evil and thus [[spoiler: had to be killed off permanently]].
* Happens to Nick in ''Series/HowIMetYourMother'', who was originally depicted as a hot guy who was both mature and had subtle snarker tendencies. But later in season eight, he becomes "girly", overly sensitive, has [[GranolaGirl Granola Guy]] tastes and [[TheDitz is a complete idiot.]] There was attempted justification that he was an idiot all along but was too hot for Robin to notice that.
** In the same episode that it was "revealed" Nick was overly sensitive, it was "revealed" that Victoria was a total slob at home, something that has never been hinted in her previous appearances and given her occupation as a highly skilled pastry chef, it seemed rather unlikely. Thankfully, it was averted in the episode that she and Ted broke up where her being a slob wasn't what caused them to break up and Lily acknowledged that Victoria had valid reasons for breaking up with Ted because of Robin.
* In ''Series/KamenRiderKiva'', there's a LoveTriangle between [[TheCasanova Otoya]], [[DefrostingIceQueen Yuri]], and [[TallDarkAndSnarky Jiro]]. Jiro proposes to Yuri, but then in order to have Otoya win her heart, Jiro is rapidly derailed into an obsessive lover who [[IfICantHaveYou tries to kill her]] because she doesn't want to marry him. All is moot anyway because Otoya then breaks Yuri's heart by dumping her for Maya, the mother of the show's protagonist.
* ''Series/DocMartin'': Louisa reunites with her ex-boyfriend, who accepts a job in London after asking her to marry him. So she dumps him because he's disingenuous about living a life together in their beloved village, and not so much because he's [[TheFundamentalist an insufferable Jesus freak]].
* ''Series/SilentWitness'': Nikki and Harry's underlying mutual attraction was extremely popular with fans (and later, after Harry left, Nikki turned out to have exactly the same attraction with [[ReplacementLoveInterest Jack]]) so, if either of them gets a love interest who isn't killed off, this is what tends to happen instead. A typical example is in the story "Safe" where Nikki begins dating a paramedic that she met at a crime scene. He initially seems to be the perfect guy, but she soon works out that he's cheating on a wife or girlfriend with her, and he turns out to have a short temper too. The last straw comes when he goes on a racist tirade against the mother of two murder victims, causing Nikki to finally wise up and dump him (much to the delight of Harry).
* ''Series/TheVampireDiaries'' derailed Tyler harshly twice, first in favor of Klaus and Caroline, and then in favor of Caroline and [[spoiler: Stefan]].
* ''Series/DowntonAbbey'': In series five, Anthony Gillingham suddenly becomes clingy, demanding and possessive of Mary (even giving the implied threat of ruining her reputation if she tries to break up with him) in order to have her warm up to Charles Blake.
* ''Series/OnceUponATime'': Done in an interesting (if somewhat convoluted) manner in regards to the Regina/Robin Hood/Maid Marian triangle. Season 3 ended with Regina and Robin Hood falling in love and starting to date each other, but then suddenly Maid Marian (Robin Hood's wife who was originally dead by the present story-line of the show) is accidentally pulled out of time into present-day Storybrooke. Obviously, Robin goes back to her (since it's his long-lost wife and he made a commitment to her), making Regina furious at losing an actual love interest. One could infer that the writers wanted Regina and Robin to stay together (seeing as how quickly Robin and Regina hit back off when Marian becomes incapacitated in the beginning of Season 4), but with Marian present, they couldn't. In the end, [[spoiler: Marian [[ShockingSwerve quite suddenly]] turns out to be Regina's spiteful older sister Zelena (the real Maid Marian turned out to be dead after all)]], leaving [[spoiler: Regina and Robin]] free to continue their relationship without a hitch.
* ''Series/DropDeadDiva'': Owen French, a sweet judge who dropped his own vacation plans to spend a romantic time with Jane, suddenly becomes a spiteful and petty JerkAss after [[spoiler: Grayson kisses Jane on her wedding day]]. While Jane should have [[PoorCommunicationKills explained what]] [[IdiotPlot happened from the get-go]], when she finally does explain Owen refuses to forgive her for something that was not her fault and starts [[ReplacementGoldfish hitting on her best friend.]]
* ''Series/DoctorWho'' inverts this with Danny Pink, the RomanticFalseLead of Series 8. He is a genuinely worthy person and caring boyfriend to Clara Oswald, but because she is a ControlFreak who cannot bear to give up her wacky, dangerous adventures with the Twelfth Doctor despite Danny's pleas, she constantly lies to both men to keep up her relationships. When she's ''finally'' ready to settle down with Danny and be completely honest with him, [[spoiler: he is killed in an accident ''and'' subsequently learns how deep her relationship with the Doctor truly goes]], and he thus ends up on the losing end of the relationship in the SeasonFinale. Clara is the Doctor's DistaffCounterpart and chaste lover from "Last Christmas" onward, and that relationship comes to a bittersweet end in the Series 9 finale arc.
* ''Series/{{NCIS}}'''s Jake Malloy (husband of Ellie Bishop) goes from being a loving, adoring spouse to a cheating one. Adding insult to injury, the fact that her next boyfriend was killed off in two episodes indicates that this was done for no other reason than to make her have the same tragic, screwed-up love life that nearly everyone else does.
* In ''Series/BlackLightning'', Anissa's girlfriend starts the show as loving and compassionate, and their relationship is loving and full of passion, to the point where Anissa is comfortable telling her about her growing powers. Then, in episode 3, the girl inexplicably becomes jealous, paranoid, and racist, and Anissa suddenly claims that the relationship has been going downhill for awhile. No sign of that has been shown in the two previous episodes. All this seems to be done to allow Anissa to hook up with Grace, who might be more supportive of her becoming a superhero.
* Stuart Rosebrock on ''Series/{{Coach}}''; when he's introduced he has nothing but devotion to Kelly, [[DatingWhatDaddyHates despite Hayden not liking him]] and, though they have a few arguments during their dating & eventual marriage, are shown to be a good match. Then comes the season 4 premiere "The Kick Off & the Kiss Off," where he got a job on a popular kids show over the summer in Los Angeles, and suddenly, he comes back, [[TookALevelInJerkass loving LA and thinking he's too good for Minnesota]], having apparently met someone else on the show, and leaves Kelly behind just like that, despite him ''having shown nothing but love and affection for her before then.'' [[note]] Granted, this was because Kris Kamm was leaving the show, but there could've been a better way to have him leave. [[/note]]

[[folder:Newspaper Comics]]
* Towards the final years of ''ComicStrip/ForBetterOrForWorse'', any non-Anthony entity that Elizabeth showed any romantic interest in, no matter how sweet and kind, were eventually shown to be cheating on her, [[StalkingIsLove stalking her]], or otherwise completely disrespecting her. The record being her date to a wedding reception getting drunk and falling asleep the same night. Note that Anthony did in fact stalk Elizabeth and emotionally cheated on his wife, but these were brushed aside because he was ''[[CreatorsPet Anthony]]''.
** The dumbest break-up was with the helicopter pilot. First Liz mistook his sister for a secret girlfriend, then he said he couldn't be tied down.
** Speaking of Anthony's wife: Similar to the ''Fraiser'' example Theresse had ''never'' been portrayed in a good light. She's jealous of Liz at her own wedding, is [[AmbitionIsEvil very ambitious]], has no desire to be a mother ([[NotWantingKidsIsWeird the most unforgivable sin in the Foobiverse]]), had Anthony do all the childcare, and in her final appearance [[spoiler: abandons her child forever]]. Then again there's the fact that Anthony pretty much ''forced'' her to have a child and ignored what sure looked like post-partum depression.

* ''Theatre/LoveNeverDies'', the sequel to Creator/AndrewLloydWebber's ''ThePhantomOfTheOpera'', does this to poor Raoul. In the first show, he was Christine's sweetheart: dashing, brave, and protective of his childhood friend. In the sequel, set ten years later, he is an alcoholic gambler who's blown his fortune, ignores his ten-year-old son, and is snippy with his wife. This is all an attempt to justify Christine considering running back into the arms of ''a mentally-unstable stalker and murderer''.
** Actors portraying Raoul in the original ''ThePhantomOfTheOpera'' have even been given direction to play the character as brash and unpleasant, to make it more of a seamless fit with the sequel show. It's quite noticeable if you've seen the show before ''Theatre/LoveNeverDies'' came about, and after.

[[folder:Video Games]]
* ''VideoGame/FireEmblemGenealogyOfTheHolyWar'' has two characters, Eldigan and Raquesis, who give huge BrotherSisterIncest vibes despite Eldi being married to a lady named Grahnye and having a kid with her, Ares (who becomes a playable character in the second part of the game). One of the artists hired to make manga adaptations of the game, Mitsuki Oosawa, is an Eldigan/Raquesis shipper. What does she do? Aside of erasing one of Raquesis's prospect love interests, [[PunchClockHero Beowulf]], [[AdaptedOut she writes Grahnye out of the story]]... via introducing an {{Expy}} of her named Iria and making her a HUGE RichBitch who clings to Eldigan and hates Raquesis to death, while cranking up the canon incestuous subtext UpToEleven. This gets so bad that Iria gives Raquesis permission to join Sigurd's group [[UriahGambit solely to get her killed in battle]], and [[spoiler:when Eldigan is executed, she barely shows any pain for it, and quietly gloats about how unhappy Raquesis must be]].
** This is actually weird, since the ''other'' LoveTriangle she used in the manga averts this trope. The three parts of the deal (RebelPrince Lewyn, LadyOfWar Ferry and GenkiGirl Sylvia) are portrayed in very human ways: while the manga leans more towards [[spoiler: Lewyn/Ferry]], the loser in this triangle ([[spoiler:Sylvia]]) doesn't show bitchy or evil behavior in any way. In fact, she's given HiddenDepths and shown in an even kinder light than in the canon game!
* ''VideoGame/TalesOfDestiny'': In the original game, Ilene Rembrandt is presented as a hard-working and idealistic woman Stahn very easily gets along with. The pair go on a date that goes quite well. But Stahn needs to end up with [[{{Tsundere}} Rutee]] (who is violent and aggressive towards him, and generally not a very good suitor) in the end. So what happens? Ilene is shown to believe in [[spoiler: Hugo Gilchrist's]] FinalSolution and commits suicide when she loses to the party. Her situation is [[PlayerPunch played sympathetically]], but it's still a jarring twist. In the remake, the date and all elements of the LoveTriangle are removed, making it simple CharacterDerailment.
* Penelope Mouse of the ''Franchise/SlyCooper'' games is an egregious example. She is introduced in [[VideoGame/Sly3HonorAmongThieves the third game]] as a smart NiceGirl who begins dating Bentley at the end [[PairTheSmartOnes because of]] [[BirdsOfAFeather their similar traits]]. However, [[VideoGame/SlyCooperThievesInTime the fourth game]] inexplicably retcons her into a greedy BitchInSheepsClothing who only wanted to use Bentley to become rich, giving him a reason to dump her.

* ''Webcomic/{{Endtown}}'': Holly Hollister's [[CharacterDerailment/{{Webcomics}} Character Derailment]] hit its most vicious point at about the same time the author introduced a new love interest, Kirbee, for which he himself has expressed great affection, holding her up as his favourite type of person (the [[ThePollyanna eternal optimist]]). This is after spending the previous several years drawing large amounts of shipping art of Holly and her partner Wally before suddenly stopping around the time he had to go on a hiatus from the comic due to a bout of serious illness that threatened him with the loss of his legs. Notably, Holly had never previously lashed out at anyone close to her during her periods of infirmity (instead tending to flee and once attempting suicide), only doing so once plot circumstances meant it would handily push Wally away from her and into the arms of Kirbee, who had been made part of the main cast during the same rewrite that added the event that shattered Holly's remaining sanity.

[[folder:Western Animation]]
* ''WesternAnimation/TheSimpsons'' used this in an episode where, before they were married, Marge goes to college and leaves Homer for a [[StrawCharacter Strawman Liberal]] professor who is smart, worldly, and seemingly more attentive to her, while he actively sets out to make Homer's honest love and devotion look like pig-headed, StayInTheKitchen [[StrawMisogynist misogyny]] (which could itself be seen as [[InvokedTrope invoking this trope]]). Once they start dating, the professor suddenly becomes condescending, passionless, and passive-aggressively misogynist, the final straw being that he's anti-marriage. He'd been a pretty insufferable guy up to that point, but became significantly worse once he'd got rid of the competition. Homer in fact lampshades it at the end; "don't worry, kids, she'd never have stayed with that professor... unless he'd been a ''little'' nicer to her at the beach!"
* ''WesternAnimation/TotalDrama'' had a sort of version of this in the second season. Trent became jealous of Duncan and Gwen's friendship, which makes some sense, but also became a ridiculously-clingy stalker and, weirdest of all, out of nowhere developed a supposedly-longstanding obsessive-compulsive fixation with the number nine. Seriously. Different than many of these examples because Gwen did ''not'' immediately run into another man's arms, though the show keeps teasing the idea of her and Duncan getting in a love triangle with Duncan's girlfriend Courtney. Basically, the whole situation was badly-done.
** Add Courtney's CharacterDerailment in ''Total Drama Action'' at the list, as well...
** The LoveTriangle between Duncan/Gwen/Courtney is a fact in ''Total Drama World Tour''... and eventually Duncan cheats on Courtney for Gwen (destroying their budding friendship) with no explanation or motive, with Courtney receiving further derailment. Enough for Heather to compare Courtney to crazy Izzy.
* Averted/subverted/played with in ''WesternAnimation/XMenEvolution'' after [[BrokenMasquerade the mutant revelation]] and the series cut up most of its romantic plot threads:
** [[JerkJock Duncan]] and Jean broke up because he acted like a jerk. However, he always was a jerk and Jean hadn't expressed a lack of interest in the relationship any more beforehand because of his jerkitude. Only now he told Jean he was willing to "overlook her problem" and she could use her powers to help him cheat on tests. He totally crossed the line when he began attacking mutants with guns and bombs!
** Scott and Taryn broke up in a slightly straighter example as while she was always nice, she apparently no longer wants anything to do with him, but then again she just found out he's a mutant who could accidentally smash ''planets'' with his ''eyes'', and who knows what could've happened if given the chance to see beyond that.
** Kitty and Lance broke up because she just found out he was a jerk and a villain, but Lance himself had previously been both a jerk and villain only attempting a HeelFaceTurn [[DatingCatwoman to be with Kitty]]. In some ways their breakup made a lot of sense considering the fact that, before they broke up, he returned to 'villainy' alongside the Brotherhood and Mystique, and still had some contempt for the X-Men. And, just so he wasn't forgotten, he got an episode of CharacterDevelopment later and his own personal CrowningMomentOfAwesome which doubled as a PetTheDog moment. [[RuleOfCautiousEditingJudgement But,]] [[RonTheDeathEater some would rather think he was always an ass or worse]] [[BrokenBase while others]] [[DracoInLeatherPants would rather think he was always a sweet guy with a troubled past and bad friends]].
* ''WesternAnimation/FamilyGuy'': Quagmire gets engaged to a calm and attractive maid. Throughout the episode, the relationship was loving and Quagmire even lost interest in other women. Peter and the gang's attempts to get Quagmire back to his old womanizing ways fail, up until the wedding reception, where Peter's actions with Lois remind Quagmire of what he really wants. Then his cheerful patient bride to be is revealed to be a self-destructive {{Yandere}} out of nowhere, therefore absolving Quagmire of getting out of the relationship. StatusQuoIsGod in this show, so the relationship was unlikely to survive the episode.
** Similarly, in another episode, Brian ends up dating an older woman - attractive, smart, a decent head on her shoulders despite her age (which isn't even really that old), and despite the [[JerkAss entire family]] laughing at her for it, [[HeartwarmingMoment Brian ends up proposing to her]] and it seems everything is going to be okay...until out of nowhere (this is where the trope comes in), she starts calling him for lunch far too early to be reasonable, complaining about her hip, and giving 'old-fashioned' names to things. This is, again, out of nowhere and doesn't match up with anything she'd done before, but as stated before, StatusQuoIsGod and the relationship would not have survived the episode no matter how you cut it.
* ''WesternAnimation/{{Futurama}}:'' Season 6's "Proposition Infinity," which uses [[{{Robosexual}} human/robot relationships]] as a metaphor for gay marriage, does this to [[ExtremeDoormat Kif]]. He's suddenly {{Flanderized}} into such a wuss that he's afraid to watch cooking shows because they contain chopping, and [[AsianAirhead Amy]] suddenly becomes utterly disgusted with him, when it was Kif's sweet nature that attracted her to him in the first place. All so Amy can wind up in a relationship with [[JerkWithAHeartOfGold Bender]] that doesn't last to the end of the episode, the last scene of which has her reconcile with Kif. [[SarcasmMode Apparently this was easier than just creating a one-off human love interest for Bender]], or using [[InterspeciesRomance human/alien relationships]] for the metaphor instead or something.
* In Season 6 of ''WesternAnimation/TotallySpies'', [[spoiler: Blaine cheats on Clover with Mandy]] in a very out-of-character moment for him that seemed shoehorned in for the express purpose of [[spoiler:getting Clover single again so she can resume flirting with guys]].
* Julie admitting in the ''WesternAnimation/{{Ben 10 Omniverse}}'' episode "Rules of Engagement" that she never liked Mr. Smoothies, only faking it in front of her ex-boyfriend Ben despite the fact that she is seen sharing smoothies with Gwen back in ''[[WesternAnimation/Ben10AlienForce Alien Force]]'' without any objections.

[[folder:Real Life]]
* People in relationships tend to ignore certain flaws in favour of more desirable traits. If a partner has a {{Jerkass}} moment, then this can cause all those flaws to become much clearer e.g. [[HarsherInHindsight a jocular comment can sound more like a veiled attack if the partner drops the charm]].