Unrequited Love Switcheroos in Literature.
- The 39 Clues: Ian didn't seem to care much about Amy as he was faking feelings for her so he could run off with her clue, but as soon as she started getting over him- or, as soon as she had convinced herself that she had- he seemed to realize his genuine feelings for her. Too bad about life getting in the way....
- In the Anne of Green Gables series, Anne's childhood friend Gilbert Blythe has a crush on her for about two and a half books. When he finally proposes to her, she rejects him because she isn't in love with him. Near the end of that book, Anne realizes she actually is in love with Gilbert, but she is convinced he is engaged to another woman. Luckily, the engagement turns out to be just a false rumor.
- Occurs in the High School books from the Betsy-Tacy series. In her Freshman year, Betsy becomes infatuated with Tony and is heartbroken that he falls for someone else, with him only seeing her as a friend. She gets over it at the end and realizes that they are better that way. At the beginning of their Senior year, Tony begins to show that he's falling for her but Betsy is no longer interested and is more excited about her elusive crush, Joe, finally becoming interested in her.
- Bridge to Terabithia has this, in a sense. Leslie loves Jess, but he has a crush on Ms. Edmunds (his teacher), and only realises his feelings for Leslie (and her feelings for him), after she dies.
- Suggested in Dinoverse. Bertram pined after Candayce even when they both were in dinosaur bodies. When after a separation she kissed him - or tried, they both had beaks - he happily said he was cured and stopped mooning over her. From Candayce's reaction this wasn't what she wanted to hear. When they were both human again she tried again, and this time had the desired result.
- Onegin/Tatiana in the Russian novel/opera/film Eugene Onegin. Though Tatiana still loves him, but she's married to someone else now, and he treats her better than Onegin ever did or will.
- This is the plot of Felise by Algernon Charles Swinburne. The poem's narrator is turned down by the woman he loves. A year later she comes back to him, having realised that she loved him all along. Unfortunately, though he's by no means over her, her first rejection was sufficient to irredeemably wreck their relationship and the poem is his way of saying goodbye forever.
- Central to the plot of Wendelin Van Draanen's novel Flipped, which starts with Juli's crush on her new neighbor Bryce (who finds her to be a really annoying know-it-all), shows her feelings changing from said crush to disillusionment as they grow up, and ends with Bryce's own growing feelings for Juli going as far as ruining his own social rep among his peers to show how much said feelings have grown.
- In Gesta Danorum, Ladgerda is initially uninterested in Ragnar Lothbrog and sets a bear and a dog on him when he comes to ask her in marriage. Ragnar kills the animals and gets his will. Years later, when Ladgerda has already borne him three children, it occurs to Ragnar he cannot trust her because she sicced the beasts on him, so he divorces her and marries Thora instead. But Ladgerda still loves him and when Ragnar is hard-pressed by the usurper Harald, she comes to his aid with a fleet and once more saves him from defeat.
- In Gone with the Wind Rhett doesn't fall for someone else, but he loses interest in Scarlett over a period of some years, as her indifference, mistreatment, and obsessive pursuit of Wilkes wore away at his feelings for her. By the time their daughter Bonnie died, it was mostly over before Scarlett even fully grasped that it had started.
- The title character in the Harry Potter books has a crush on Cho but is fully aware that Ginny has a crush on him. After things don't work out with Cho, and Ginny has already moved on, Harry develops a crush on Ginny after dealing with a bout of jealousy — a Green-Eyed Epiphany — over Ginny's new love interest. This is somewhat subverted though, as Ginny later admits that she'd never gotten over her feelings for Harry, and was dating other boys while waiting for him to come around.
- It's also implied that Cho develops feelings for Harry, but it's pretty much too late by that point.
- While not played entirely straight this trope appears in The Hunger Games. By the time Katniss realizes she's in love with Peeta, he has been captured by the Capitol. They manage to save him and she expects a very happy reunion. Instead he tries to strangle her because he's been brainwashed into thinking she's a mutation who wants him dead. Ouch.
- In A World Just Right has Johnathan Aubrey, a teen who can create worlds on a whim and give them whatever parameters he wants. To soothe his aching loneliness, he creates a world where he can date his dream girl, Kylie Simms, and splits his time between it and the real world. However, when he accidentally tries to kiss the real Kylie, she starts becoming more and more infatuated with him, while the Kylie he created to love him becomes cold and distant. He's not happy with the change. Eventually he finds out that the real world momentarily intersected with his fake one, causing the two Kylies to begin to merge. He has to help facilitate this merger, lest the Kylies destroy each other.
- A Russian book called Militia Sergeant features this in a classic variant. Nikolaj Zacharow, a young militia officer, and Natasha, a daughter of a factory director, meet, but Natasha wants him to make a career, and not be stuck in militia, so she abandons him. Years later they meet, he is already a captain, her love for him comes back, only for him to reveal that he is already happily married and only agreed to meet her to say goodbye.
- Ruslan and Ludmila: Finn spent fifty years desperately pining after the gorgeous Naina, until, after finally casting a love spell over her, he discovered that she is no longer gorgeous.
- The Russian adaptation of The Shadow by E. Schwartz features this. First, the writer and the princess fall in love, but then the shallow princess abandons him for his shadow. In this variant, the writer survives and defeats his shadow, the princess is once again in love with him, but now he is only interested in Annuncuiata, another girl.
- A Polish children poem Żuraw i czapla {end: A Crane and a Heron) by Jan Brzechwa plays this for humor, with one of the titular birds falling for the other and being rejected only for the other bird to come around now that the first one wants nothing to do with them. The switch happens multiple times and the narrator notes love cannot happen unless both parties are willing at the same time.
