Marjane (narrating): Nevertheless, somewhere inside, I was reassured. It was easier to accept that he was gay than that he had preference for Ingrid or he found me ugly.
This girl is responsible for a guy in a Transparent Closet realizing he's gay, and inversely this could be a guy responsible for a closeted woman realizing she's a lesbian. The situation is usually that after their first kiss (or sexual encounter in some cases) he realizes that he doesn't feel the right kind of chemistry with her, and outs himself to her and breaks the relationship. Usually this requires that the ex profusely reassure them that "It's Not You, It's Me" and that they'll eventually find someone who will return their feelings. On the positive side, they may end up on the good end of Just Friends and have a high chance of becoming Amicable Exes.
This can be Played for Laughs or Drama with the girl fretting that she's a terrible romantic prospect, or such a shrew or so bad in bed she literally drove the guy into forsaking his heterosexuality. Can be played for extra laughs/tears by her having several boyfriends do this in a row, and then with Mom calling to ask whether she's "turned another guy gay".
In the least conflictive examples, the guy will realize due to outside events rather than from their (lack of) chemistry. Sometimes it'll happen after they've broken up, which may or may not be a relief to the girl. In comedies, this can be a funny way of Cleaning Up Romantic Loose Ends.
In the case of a lesbian coming out to her boyfriend, a comedy will usually imply that the guy is so bad at sex or such a perverted pig (or both!) that she becomes a lesbian out of disgust.
This can of course be Truth in Television. This trope is in a way the Inverse of Closet Key, rather than a lack of reaction from a heterosexual partner, it's a same-sex attraction leading to the epiphany. It's worth noting that some women may become Fag Hags who Settled for Gay because All the Good Men Are Gay.
- Ouran High School Host Club: Ryoji to his wife Kotoko. He's a gay man, but she managed to open his heart to a woman, and after her death, Ryoji remained gay and single, saying that Kotoko is the only woman he loves.
- Seraph of the End: Both Guren and Shinya to Mahiru, although the circumstances are vastly different. For Guren, Mahiru is his first and only love, so after she died and turned to a demon, having a vast amount of her humanity wiped off, he never looks for love again whether female or male. For Shinya, she was supposed to be his fiance, but since she loved Guren, he didn't stand a chance. Their relationship became more and more strained until he got totally done with her and completely switched his interest to Guren instead. And in the present, when asked what his preference for the opposite sex is, he simply replies along the lines of: "My fiance was like that, so I got tired..."
- In Persepolis, Marjane's boyfriend Enrique outs himself. Previously she had worried that he wasn't interested in her after they slept in the same bed but didn't have sex, and when later she encountered him talking to a prettier girl.
- In Young Avengers, it's mentioned that Ultimate Nullifier (the character, not the cosmic superweapon) was this for America Chavez. America herself finds the whole thing embarrassing.
- In the last volume of Scott Pilgrim, at the end, Scott learns that Steven Stills got a boyfriend. Scott is besides himself about how he feels Stephen's (now ex) girlfriend for the majority of the comic, Julie, turned him gay.
- In The Birdcage, the last heterosexual relationship Armand was in involved a woman named Katherine, which resulted in their son Val. However, Katherine didn't want the trouble of raising Val, so Val has been raised by Armand and his lover Albert. Everybody seems to be okay with Val being raised by two dads, until Katherine finds out Val's getting married, and she wants to meet the parents of Val's fiancee. That would be one thing, but considering the whole movie is a "Fawlty Towers" Plot, it's one more thing that Armand and Val have to work around before their lie about being a conservative family in a bad situation comes crashing down on their heads.
- The plot of Saved! is set into motion by this.
- Zach in Shelter had a longer on-off relationship with Tori before realizing he was gay. Tori, by the way, knew it earlier than he did. While their relationship got more and more problematic over time, Zach truly cared about Tori and is sad to have hurt her. They manage to become good friends eventually.
Zach: You're the only reason I wish I wasn't, you know? None of that other shit matters. The only thing that really sucks is that I always wanted to be everything to you. I dreamed of providing you with anything you wanted and needed.
- Invoked by the protagonist in What Women Want, to spare the feelings of a girl he's slept with and moved on from. He tells her he's gay so that she won't think she's a big loser who can't hold on to a man.
- Discussed in Victor/Victoria when Toddy is trying to convince Victoria that, yes, she can convincingly pretend to be a man:
Victoria: Men have Adam's apples.
Toddy: So do some women.
Victoria: Name one.
Toddy: Nana Lanu.
Victoria: Nana Lanu? Who's she?
Toddy: The last woman I slept with.
Victoria: When was that?
Toddy: The night before the morning I decided to become a homosexual.
- Megan's relationship with Jared in But I'm a Cheerleader was part of her realization that she was indeed a lesbian. Played for Laughs when the two are shown awkwardly making out in his car after a long slow-motion POV scene of Eating the Eye Candy during cheer practice.
- Peavy from The Rocketeer had an inversion.
Cliff: Come on, Peavy! You haven't been on a date since 1927!
Peavy': Flora Maxwell... no point in dating anyone else after that...
- 1632: Harry Lefferts insists he should be this for Sherry, as, since he is a typical redneck, he will make her lose faith in men and realize her "true" sexuality. How much is Harry being in stereotypical redneck emotional denial about having genuine feelings for Sherry, how much is Harry being a dick to a woman in her late twenties with no romantic history to speak of, and how much is friendly banter between Spec Ops operators who have been righting wrongs and blowing stuff up all over Europe for three years, is up for debate.
- In You Know Me Well, Katie claims that dating Quinn in third grade was this for both of them.
- How I Met Your Mother: Robin lost her viriginity to a gay guy, only not really because he'd barely gotten in before he stopped and announced, "Yeah, I'm gay." Considering that the guy was as camp as you could be without starring in The Birdcage, and his room looked like Liberace's sewing room, she should really have seen it coming.
- Ted was also this for the mother's roommate Cindy.
- On The IT Crowd, Jen plays this to a man whose sexuality is a mystery through most of the episode. At the end he breaks down and cries that he only went out with her because she looks a bit like a man.
- Seinfeld also plays with the trope. After seeing his ex-girlfriend Susan with another woman, and confirming that she started dating women right after they broke up, he starts worrying that being with him was such an awful experience that it put her off men entirely. Even though Susan tells him that he's being ridiculous, his fears are all but confirmed when another of George's exes shows up... and immediately starts flirting with Susan. Susan would later go back to men and actually get engaged to George. Apparently her lesbianism "didn't take".
- The same episode also humorously inverts the trope. Susan's girlfriend, who has never been with a man in her life, is turned straight after a night with Kramer.
George: Amazing. I drive 'em to lesbianism. He brings 'em back!
- The same episode also humorously inverts the trope. Susan's girlfriend, who has never been with a man in her life, is turned straight after a night with Kramer.
- This is the college backstory of Will & Grace, as revealed in a flashback episode.
Will: But... Don't you see what a compliment that is? I mean, I mean, I love you, so if I can't make it work with you, then it'll never work with any woman, because you're perfect for me.
Grace: That is not a compliment. A compliment is, "You're sexy; you turn me on," not, "One look at you proves I'm a queer."
- It becomes a Running Gag that many of Grace's ex-boyfriends turned out to be gay.
- Happily Divorced averts this trope. In the case of that show, the husband has always been gay, but he doesn't reveal it to his wife until they've been married for a long time and he wants a divorce so he can live a gay life. Bonus points for being based on star Fran Drescher's real life.
- On Cheers, Rebecca's boyfriend from high school(played by Harvey Fierstein) pays a visit and she finds out she was this to him.
- Friends: Ross' first wife turns out to be a lesbian, while pregnant with his child.
- On Roseanne, Arnie was obviously bummed when his ex-wife Nancy came out of the closet. His friends tried to jokingly reassure him that he was just so virile that Nancy knew no other man could compete.
- In Hollyoaks, John-Paul's failed romance with Hannah leads him to realize that he is actually gay and in love with his friend Craig. This was also used to kick off Hannah's controversial eating disorder storyline as she refused to accept his sexuality and believed it to be a nice way of telling her she was ugly.
- On The George Lopez Show George learns that a man Benny may have slept with while drunk could be his biological father. He has only been with men since their night together, however, and Benny refuses to believe that someone she slept with could turn out to be gay. It turns out she's right—they never had sex, Benny just passed out drunk.
- Absolutely Fabulous: Edina, Edina, Edina. First husband? Identified as homosexual and left her. Second husband? Became The Alcoholic, and left her... to realize that he may be bi (if not just deeply closeted gay) afterwards. Guy she banged really loudly so she can get him, his wife and their baby out of her house? Came out as gay several seasons later. Really, you could make a case that she's a walking Brown Note to heterosexuality itself, and that intercourse with her leaves straight sex ruined.
- Happy Endings: Penny was this for Max. They're Platonic Life-Partners now. One episode of the gang on an unaired season of The Real World had Max having a lot of Have I Mentioned I Am Heterosexual Today? moments.
- Invoked and inverted on Penn & Teller: Bullshit!. During one episode, they interview a man who claims to be able to "turn gay guys straight":
Penn: Which is funny, because I don't think he's that unattractive.
- On Party of Five, Sarah turns out to be this for Elliot.
- On 8 Simple Rules, Rory goes to great lengths to make his date fall for him. Even she thinks it should have worked, but it didn't, so she comes to the conclusion that she must be gay, and asks him where his sister Kerry is.
- In Girls, Hannah finds out she was this to her college boyfriend. She doesn't take it very well.
- Glee had a fair share of hetero relationships involving gay characters, but unsprisingly tends to avert the trope. Most of the gay characters shown in some sort of hetero relationship (Kurt, Santana, Blaine, Karofsky, ect.) are aware of their gayness while being in said relationship. Those relationships are often one-sided or mutual bearding, mostly as a part of an Armoured Closet Gay act, or maybe a sexual experiment. Seeing how Glee doesn't really believe in bisexuality, and in spite having a Cast Full of Gay has only one bisexual character (Brittany) and a whole lot of biphobic gays, the writers seem to be more fond of the gay Closet Key trope is their engine of choice in their numerous coming out stories.
- In The War at Home, while Kenny was living with the Golds, his date Dylan stops by, which leads to hilarity, as Hillary discovers that it's her ex-boyfriend.
Hillary: Wait wait wait, you mean my Dylan, is now your Dylan?
David: Who knew Hillary? You're the Gaymaker. The last stop on the train to Gay-ville. Sprinkle on a little Hillary, and (waves hand)HELLO!
- Bonus points, in that Hillary once dated Kenny, but Kenny was utterly repulsed by kissing her.
- Josh is Elena's first and last het romance on One Day at a Time (2017). She realizes that he's exactly who she'd date if she liked boys, but she just doesn't.
- In A Chorus Line, Gregory Gardener realizes he's gay when making out with a girl.
- In Blip, K was Bang's last girlfriend before he realized he was gay. They remain close friends afterwards.
- Happened (only twice!) to Davan in Something*Positive, though it's not explained why the girl switched teams.
- PeeJee's ex-almost-fiancée turned gay some time after they broke up. However, they broke up because he was cheating on her with another woman, so she might not have been the last romance.
- Robin is this for Ethan in Shortpacked!. She already suspects that he's gay, but is pursuing him anyway. He's not interested. She gets pissed off when he bangs a chick, and when he asks why she shouts he's supposed to be gay. Confronted with this, something goes click in his mind, and he embraces the gayness.
- Melissa & Justin in El Goonish Shive. Melissa is also inadvertently responsible for outing him in the more traditional sense, since afterwards she told her sister, the town's biggest gossip, about it.
- Nanase also has this with Elliot. Unlike Justin, Nanase dated more guys before dating Elliot, looking for the right one, but Elliot is the only one we know of where she admitted it wasn't working out. She did not, however, immediately come out as gay after breaking up with him. That took a Closet Key in the form of Ellen, Elliot's opposite sex clone. It is that kind of comic.
- More recently, after Elliot and Sarah break up while remaining Just Friends in very good terms, people assumed that this trope was the only way that'd happen, and started the rumor that he was gay. Nothing could be further from the truth, though: actually both of them wanted to break up.
- Played for laughs - in a slightly cruel way - in Girls with Slingshots. Jamie has a period where she starts questioning her sexuality. Thea, Hazel's lesbian boss, suggests they sleep together to find out. They do and Jamie decides she isn't a lesbian after all. After she leaves, Thea is shown adding about the fiftieth line to a 'number of girls turned straight' chart with a sigh.
- In Sticky Dilly Buns, Jerzy describes himself as having passed through a bisexual phase before concluding that he was gay. It's not clear who his last het romance was with, but it may have been Angel, or possibly even Zii.
- In Questionable Content Marten's parents Veronica and Henry ended up getting divorced when he was a kid after his father realized he was gay. Despite being an unsuccessful couple they're excellent parents to Marten and Veronica ends up giving a speech at his wedding talking about this and wishing him the best in his new marriage.
- The Class Menagerie had Mikey being pursued by the flirtatious Lisa for most of the series run, only to reveal near the end that he's been a closeted gay man this whole time, and he's been in denial, hoping that having Lisa's interest would "spark" something for him. She's the first person he's ever told about it, having been deep in the closet since high school.
- Condie Ling from Rick & Steve: The Happiest Gay Couple in All the World turned Rick gay in college (in his own words). She's since become a Fag Hag (with suicidal tendencies played for laughs) since it is inferred that he wasn't the only person to whom it happened.
- On King of the Hill, Peggy—who told Hank that she was a virgin before they got married—admitted that she had once had sex with a male friend who was unsure if he was gay.
Luanne: Did you fix him?
Peggy: Oh, no, Luanne, he was not broken. Just gay. Very, very gay.
- According to Clerks: The Animated Series, this is a regular occurrence for Randall. This is even more prevalent than in the movies, to the point that one girl turns lesbian after interacting with him for a few minutes. Also, all of his exes become misandrist butch lesbians.
Randall: So you're saying, after me, no other man would do?
Ex: That's one way of looking at it.
- Invoked in American Dad!. After Jeff is abducted by aliens, Snot finally manages to score a date with a despondent Haley. Afterwards he realizes that he's not really into it, being more into the chase than the catch. Because of Haley's depression (and because she has a history of going ballistic whenever she gets dumped) Steve begs him to break up with her in a way that won't set her off. Snot decides to tell Haley that he's gay, and she helped him realize that. If he can't make it work with a woman as perfect as her, then that proves beyond any doubt that he's gay. Haley accepts it with no hard feelings.