My son is currently watching the anime series Ranma ½, and this morning he told me about a trope that the show is famous for: the Love Dodecahedron (from TV Tropes):

Love Triangles are stressful and often heartbreaking. Add five or ten more people to the mix, and instead they become comedy: Characters A, B, C, and D all love character E, who might love any of them, but can’t commit for reasons of honor or basic wishywashiness. There’s also character F, who might love E, and whom he might love back, but they get on each other’s nerves so it’s hard to tell. Meanwhile, G is sweet on C while H and I both love A. Except on alternate Tuesdays, when H’s third cousin from Osaka expresses her intent to marry Character F’s dog, who has an odd thing for D…

Read More (don’t miss the examples, for everything from Buffy the Vampire Slayer to Pride and Prejudice, at the bottom of the page)