Most Helpful Guy
It's different for a guy to interact with a girl he's into rather than a girl he isn't into. If he's not into a girl, he feels as though he can be himself since he doesn't case much about whether or not she sees him as a potential partner. If he is into a girl, he feels like he has to watch what he says around her and not say the wrong thing or else he's locked himself out of a relationship with her. The best way to avoid that, the guy thinks, is to just not interact with her. So that's why guys avoid girls they like.