@Wrex
Serious answer: She's got no concept of "Personal Space", which some people, believe it or not, will find EXTREMELY off-putting. On top of this is the fact that he, as an adolescent going through puberty means that there's tonnes of new sensations and thoughts he has to deal with from his hormone-overloaded mind, including and especially Testosterone, which is linked to heightened aggression. So, basically, you have a guy who looks like he loves his personal space/private time dealing with an onslaught of feelings of aggression and sudden arousal at inconvenient times being clung to by a girl who not only is not allowing him his space to breathe and just generally figure himself out, but she actively ignores his attempts at actually helping her with her main problem (making friends).
Basically, he's a stand-offish teenage boy dealing with teenage boy bullshit and he's got an annoying girl who just won't leave him alone for even a second.