He didn't have a chance anyway

Men. I just don't understand them. So i was friends with this guy and he was pretty cool. We go to the sang soo do class. We were talking normal until he asked me for my number and stuff. As soon as i told him that I'm taken he turned into a freaking jerk. Why? I didn't do anything to him. Why can't he just be friends with me? Idiot. Too bad for him. Now he ignores me and just avoids me. Well it's kinda good that he gives me my space and respects that I'm in a relationship unlike other guys but he could at least talk to me- like a friend. This really doesn't bother me that much, i really didn't know him. I have enough friends.