He doesn’t wanna tell me what I did wrong why?

For context: I’m (18F) and been talking to a guy (18M for a while). We’ve hung out many times and he got distant because he got stressed due to exams. They got cancelled and I got distant too but we kept hanging out (at school). so I asked him if I did anything wrong. His reply is “I don’t wanna answer and I dont wanna start anything”. If you ask me I did nothing wrong and it’s not my fault. I’m just immature. He just said stop asking me I don’t wanna tell you

But why doesn’t he wanna tell me?