hmm, I missed the detail about the vault causing mental trauma, well that explains his behavior. Anyway, his problem would be much smaller if he tried to communicate openly with his friends. All the guys are cute btw, so that is a plus for this visual novel.
Anxiety doesn't work that way, you always second guess yourself things like "am i bothing them?" "i'm just wasting their time", "i dont want to cause trouble". Makes comunication a bitch. As for the vault Oz explains it and mentions he's worried about dave using it because of his nervous disposition.