Waifu
A "waifu" is a fictional character you feel a deep emotional connection to. The concept of forming parasocial relationships with fictional characters has been around since almost as long as fiction and fantasy has been around. The word has different meanings depending on whoever you ask - more mainstream-inclined people think that the word "Waifu" means just any anime girl you like, and think of it in an irony-poisened, insincere way, doing it as a big joke, either because they don't know better, or because they would have to present them as vulnerable, living in fright what their peers would think, and being afraid as being seen as a weirdo. Those people usually also use the word in plural form, implying they don't care about the concept at all, and just see it as quirky synonym for "anime girl". People who take waifu love more seriously are usually found on 4/a/, Wizchan, or Tohno-chan.
Waifu love can hurt a lot emotionally, and it gets only worse the more invested you are into it. Falling in love with a fictional character is more common than those ridiculing the concept admit; it's just rather seldom that people act upon those feelings and try to take it seriously.
(removed some text, because I didn't like it anymore)