Why won't he tell me what I did wrong?

Well because we were together for six months and he randomly did this. I'm not saying he has another girl or anything like that, I just want to know why he wants to be single. Is it cuz he's too busy? or cuz of something I did? I want to know..

I could certainly not know for sure, but being in a relationship involves a lot. You have another persons feelings and emotions to consider, you must conduct yourself in a respectful manner so you don't encourage other possible mates that you're available. It's just a lot of compromising and consideration, that if you were single you wouldn't have to be concerned about. It seems you're both pretty young yet, so that may be something on his mind. Maybe he's just not ready to settle down, wants to go out and carry on freely without hurting anyone's feelings. Like I said, I can't know for sure, but just a few things came to mind. Don't beat yourself up or feel badly, plenty of fish in the sea. Who knows, might turn out to be a blessing in disguise, you never know what might be around the corner!