Lmao wtf, Hiroki got pissed when he found out Rui with Ayumi, but didn't he do worse than that? Like had affair with a married man. Disgusting.
I know it's a fiction, but unfortunately there many cases like this in rl. I mean idc how much you're in love with someone, but if they're married or taken, its time to back off. You'll ruin someone's else mentally and physically, and that's not okay at all. Control your ego.
Anyway, their character development sucks as well.