p.1 hrm... didn't goes drink with cute coworker? solo bike instead... p.7 oh boy. he was damaged love. p.18 hah, he now goes with, "they're gonna cheat anyway, so lets fucks around, those cute coworker want to drink? then lets drink."
Sometimes I get the feeling authors feel the need to give a woman a ring just because of a recent cheating/NTR fad in the h-manga industry and not because it adds something to the story. The woman in the story could just as well have been single and it wouldn't have changed much.