Why won't this guy talk to me in public?

There's this boy, and I've known him for several years. I used to like him, and he used to like me, and it's sort of been like we're on and off crushing on each other for a while. We're on friendly terms right now. Anyway, he's popular and athletic, and I'm... not. At all. I'm a "freak" if you ask most people, because I dress and act differently than most kids. (I'm quiet, I like Edgar Allan Poe, I wear skirts and Doc Martens... I'm not goth or a nerd or an art freak, I'm just somewhere in between.) So, when we see each other outside of school when there aren't many people around (which is pretty often, our moms work at the same place,) we talk and he's really nice. But when I see him at school, he totally avoids me and goes out of his way to avoid talking to me. I'm so confused. Does he like me, or not? Please help. Sorry this is such a weird question. Thanks!