Honestly, rather than loving the FL it seems like he loves the idea of FL getting fucked by someone else. That's why the whole story, instead of imagining himself with the girl he keeps imagining her w/someone else. Seems to me like he's a cuckold(?) If you read his "confession" it wasn't that he confessed he loves her. He confessed that he wants to hear all the times she was having sex.

what did I just read( ̄へ ̄)
I fast read on the sex scenes because I got hooked with the ML's feeling for the FL but the author ended it in a freaking cliffhanger. if he fell in love and they're in a relationship, that means it's just okay for ML that FL is fucking other men?!! how stupid and she keeps on being a bitch. (︶︿︶)=凸