Imaginary Love Triangle

"Even those people who didn’t read Witch Weekly knew all about the supposed Harry-Krum-Hermione triangle now. Harry was getting sick of telling people that Hermione wasn’t his girlfriend."

- Harry Potter and the Goblet of Fire

We all know the classic Love Triangle and all its many configurations. It can be a major source of drama in any situation, but there are times when the love triangle only appears to be there. Maybe one of the corners misinterprets something one of the others said, or someone outside the triangle gets the wrong impression.

A number of situations could lead to this.

Bob and Alice are dating and are good friends with Claire. Bob makes some offhand comment to David about Claire. David repeats it to Emily and through Gossip Evolution Claire hears it and thinks Bob wants to break up with Alice and date her. She, however, has no feelings for Bob and tries to get Bob and Alice to reconcile their non-existent problems.

Or, Bob and Alice are very close friends, Like Brother and Sister. Charlie has a crush on Alice, but sees the pair's affection for each other and thinks they are in love. Since Charlie wants Alice to be happy, he does not pursue her.

Or, Diana sees Bob being openly affectionate to Claire when he's dating Alice. She thinks he cheating on Alice and tells Elaine who tells Frank who tells Georgia who tells Harriet. Claire may end up being Bob's cousin or just a good friend.

One defining quality of this trope is that Bob and Alice are usually completely oblivious to what everyone else thinks is happening.

Imaginary love triangles that come to be seen as real by one or more of the corners blur the line between imagined and real. They can then be represented in the diagrams in Triang Relations, either alongside the real triangle or as the real triangle. The second example above, for instance, is the "forbidden Love Triangle" a -> b <--> c when "a" fails to act. The All Love Is Unrequited triangles a -> b -> c and a -> b -> c -> a are also useful both as imaginary triangles and as real triangles to superimpose imaginary triangles on.

May overlap with Mistaken for Cheating. Practically the opposite of Hopeless Suitor. Not to be mistaken for Bizarre Love Triangle, which is completely different.

Anime and Manga

 * Fairy Tail has a love triangle existing only in the mind of Juvia, who misinterpreted something Gray said to think he loved Lucy, and thus believes her to be a rival in love. Ironically, Gray and Lucy are Just Friends and Gray doesn't seem to have an interest in love, let alone notice Juvia's affections for him. The imaginary rivalry settles down after a while, but that doesn't stop Juvia from sometimes flaunting her "progress with Gray-sama" in front of Lucy.
 * Later it's taken Up to Eleven and now she believe that she's in a Love Dodecahedron
 * Interesting example in Kannazuki no Miko: Himeko thinks she's getting in the way of Chikane and Souma's relationship. In reality, both are interested in her, and she ends up with Chikane.
 * In Virgin Love, Chiharu's knowledge of Kaoru's sex life starts to make Daigo think there might have been something between them and Chiharu decides to fan the flames. Kaoru later reveals to Daigo that Chiharu is his cousin and he's just being had.

Comics

 * Wonder Woman once laughed when a fellow Justice Leaguer mentioned the idea of Diana being romantically involved with Superman. Her heart, at the time, lay elsewhere.

Films

 * The Luke, Leia, Han love-triangle is probably the Trope Codifier, at least by the time Return of the Jedi rolls around. Once we find out Luke and Leia are siblings, their branch disappears, though Han doesn't know that until the end of the movie.
 * Played for drama in the Matt Stover novelization of Revenge of the Sith (and to a lesser extent in the movie as well). Anakin thinks that Obi-Wan is his competition for Padme after Obi-Wan visited Padme's residence once early in the morning without his knowledge. This eventually culminates in Anakin Force Choking Padme out of crazed jealousy.

Literature

 * In Harry Potter, Ron occasionally thinks he's in a love triangle with Harry over Hermione, but they see each other Like Brother and Sister. It worked itself out in the end.
 * Similarly, in Order of the Phoenix Harry mentions having to meet with Hermione about something during his date with Cho. Naturally she assumes the worst and makes a scene in the middle of the tea shop.
 * And there's the Harry-Hermione-Krum triangle in Goblet of Fire, which is entirely a product of Rita Skeeter's imagination (you'd think people would eventually take the hint that Harry and Hermione aren't like that). Harry finds it rather surreal that a professional Quidditch player three years older than him considers him an actual 'threat'.
 * In Brat Farrar by Josephine Tey, the protagonist's love interest has a romantically-inclined kid sister who tells him that she's going to marry somebody else—who turns out to be just an old friend, and already married.

Live Action TV

 * iCarly appears, even at a very long glance, to be a Love Triangle comprised of a typical Just Friends ship with Carly and Freddie, and an extreme Belligerent Sexual Tension ship with Sam(antha) and Freddie. The reality is closer to Carly and Freddie being an Official Couple as Freddie stays devoted to Carly whilst she is appearing to warm up to him romantically, whilst Sam and Freddie denying feelings for each other to the point where their First Kiss is considered Old Shame or Never Live It Down.
 * That said, there's no reason the Love Triangle can't be between Carly and Freddie, and Carly and Sam.
 * Since the episode iStart A Fan War aired, it's possible that every pairing is imaginary and none of them will happen.
 * After iOMG, it has been confirmed that Sam is in love with Freddie, so right now this is closer to an All Love Is Unrequited triangle.
 * On Dharma and Greg, Dharma's old friend visits and begins spending a lot of time with her father, Larry. Dharma begins to think she's trying to steal him away from Abbie; in actuality, the friend wanted to spend time with Larry because.
 * Noah's Arc: Interesting subversion between.
 * In Gossip Girl, Chuck assumes from spying on Blair that she and  have something going on, and so sets them up so that Blair can see   doesn't belong in their world. However, Blair is in love with Chuck, and this childishness only leads to her becoming so disgusted with him she actually does go out and find another love interest.
 * Deadly Women explore this in many episodes, where the killer will often kill the person she believes to be in love with her boyfriend/husband/stalker victim to Murder the Hypotenuse.

Web Comics

 * Briefly in Sandra and Woo. Woo thinks his rival, Tibor, is interested in Lily. Turns out she's his daughter.

Western Animation

 * An episode of Alvin and The Chipmunks had one involving a Girl of the Week, Simon, and a biker boy. Alvin convinced Simon to try out for a bike competition to impress the girl, only to find out that the biker was her cousin.
 * Total Drama Island, with its numerous Ship Tease moments, provides examples. For example, both Trent and Courtney saw themselves in a love triangle when their respective Love Interests, Gwen and Duncan, became friendly during TDA. (Though this may be subverted by the Ass Pulled Retcon in season three claiming that Gwen had always had a crush on Duncan.)
 * The inversion may be even more common, when a character is in a love triangle but doesn't notice; Cody's obliviousness to Trent/Gwen in season one would probably be the clearest example (later to be replicated with Cody/Gwen/Duncan in season three).
 * An episode of The Simpsons had the family visiting a dude ranch and Lisa falling for a cute boy (voiced by Johnathan Taylor-Thomas). When she runs into a girl who is looking for the boy, Lisa tries to get rid of her. It turns out that girl was the boy's cousin, and Lisa's actions make him hate her.