I read a yaoi doijinshi a while back and now I don’t remember what the characters were and I can’t find the doujinshi anymore.

Uke- wears glasses, constantly throwing up despite not eating, weak and skinny

Seme- dark hair, became uke’s Sex friend when uke approached him for “casual” sex. Intimidated by uke’s weight loss and ambiguous attitude he encounters a girl who looks like uke and cuts things off with uke to date his female look alike (she has a bob cut and glasses).

Girl- when she’s having sex with seme, uke bursts in and they have a threesome when she invites uke to join. She notices that seme probably likes uke and only liked how similar she looked.

B1AH

Sonna Mahou Atte Tamaru ka

kuro x Tsuki (Haikyuu!!)
By kuroquis

At least I asume that is it, cause it fits perfeclty ♥