Don't you just hate it when a person's ego can become super inflated with just an addition of two words (such as Head Boy) in front of their name?! Hopefully your crush's change in behaviour is just because he is a bit worried about his new position and the responsibilities that go with it. But if he continues to ignore you and walk around as if he's God's gift to the female student body, then its best to move on, you don't want to compete with his ego in a relationship - it's a tiring and boring task! If he can’t see how cool and special you are, then he doesn't deserve you, head boy or not.