Ugh I don't want to sound mean or something but Usagi San kind of deserved it to be punche...

i haven't actually read this manga for long time.. could you pls tell me why do you feel so? and i'm just asking ya opinion not tryna be rude.

Well I think you're not rude to ask... You need to think about how would you react if you'd found out your best friend would dated your baby sibling for many years without telling you about this... I believe his reaction was accurate... I would do the same thing... First punch his face and then apologise afterwards...