Did you reject him then? Because if you did, then maybe he's just pretending to hate you in order to feel less vulnerable around you. Maybe he's trying to get some of his pride back or something. When people feel weak, that's when their defenses are most likely to go up and a natural human defense is anger.

Also, maybe he's just changing his mind a lot about you. Maybe he was pissed at you then, but changed his mind now.