What's up with guys?

I don't get guys sometimes!
First, you think a guy likes you, then you the next thing he does is shut the door in your face. What the heck is up with that?

Advice plz!!

hmmmm...that just makes me to think...I think I am too attractive to them..lol.. or something cuz guys act like they don't want {Sometimes} nothing to do with me!!! But I don't know for sure...I just see stuff!