Why are guys confusing?

I'm trying my best to keep my focus on school and church but at school there's a boy who's become a good friend in a matter of a couple days. He's asked me for my notes but won't show me his notebook which I find suspicious since someone just wrote me a cute note which said that I know them but not well. He's kinda awkward around me and I thought it was just because we haven't been friends long, he's real open with our friend GG but when he tried to explain something and she didn't understand but I did he said "See Morgan gets it, she knows where I'm coming from!" like we've been friends forever or something.

But there's also a friend in my youth group who I've always seen as a brother who acts different every time I see him. One day he'll be super nice and texts me forever and then the next day he's making jokes of me and won't reply. I don't understand why he's so different! We've been friends for almost 9 years and it frustrates me that we're not close friends and it seems he almost hates me. What is with guys??? They're so confusing! >_<