invisible third

Working on the endless importing of all my fic into Ao3, and #Invisible Third why am I the only person using this tag? Is there some other phrase for it of which I'm unaware? ("Triangulation," but that only has one use.) Surely people frelling/kissing/dating/marrying each other because the person they're mutually interested in is unavailable/uninterested/inappropriate/dead (or alive, if characters doing the sexing are dead) is a thing? It's not even that it's a particular kink of mine, it's just... a thing. That I write a lot. Because of reasons.

(Icon on DW because Mary Anne is invisible third in the Kristy/Dawn that happens in my head sometimes. To choose an example completely at random.)

Also at DW: http://wisdomeagle.dreamwidth.org/1180161.html. Comment here, or join the conversation there, where there is/are comment(s).