Shousetsuka no Shitsukekata
I wouldn't recommend this if you are looking for an actual romance. The novelist is a manipulative bastard and the editor lets him get away with far too much. It's very interesting from a psychological standpoint though. (and, you know, sexy times) edit: WOW AND I THOUGHT THE FIRST STORY WAS WIERD. all of these are very... dysfunctional relationships. They all have happy endings (as far as that goes) but uh... just make sure to read the tags first, okay?
Similar Terms
This is creepy and dark, but also pretty interesting. The ending gave me chills.
Gesshoku Kitan
Well THIS is gonna end badly...
Birdmen
It's basically just maximum ride if the main characters got to be normal kids for a while before getting their powers. (and it hadn't all went massively downhill after the 3rd book or so)
Ibitsu na Boku wo Douka Aishite
please keep in mind that when this says it's ongoing, it's lying. this is a oneshot. I already checked on the site it's from.
Nani mo Iwanai