Oushi's friends are not good friends or they just aren't deep enough. I think they're just having fun egging oushi on even though the girl he likes is in a healthy relationship. They just like frolicking and pushing oushi in the wrong direction. I mean I get that they want to support him but to sabotage someone else's relationship without knowing them is just wrong. Unfortunately real people also do this because its fun for them to gossip anything related to romantic relationships.