Search Results: first things guys notice in a girl

Please read the whole thing before you judge me. So when I first started liking this guy, it was like my second week in a new school so I didn't know much about him. After like a month I found out he has a girlfriend and they've been dating since last year.
I was really surprised because he was obviously giving me signs that he likes me. Already on the first day I caught him looking at me and smiling and he quickly looked away. Then he used to whisper something to his friends while looking at me and smiling. I actually thought they were making fun of me. Until today I still wonder what he said about me cause honestly I did nothing wrong. I never really showed him that I like him. All I did was look at him a couple of times, but that's it.
He's still dating that girl, but I have caught him staring at me and everytime he looked away with a guilty look.
His girlfriend is giving me these dirty looks almost everytime she sees me in school and I've got a feeling she knows I like him, but then again she only saw me look at him once. So I don't know what could make her think that. I'm trying to stay away from him as much as I can. I never go to places where I know he might be. I'm being so careful and I'm trying so hard to pretend like he's another person in school that doesn't mean anything to me. Everytime we make eye contact by accident he just looks down and that makes me want to cry cause even though I know I should get over him, I can't. I'm also really mad cause he was the one who started looking at me so much. I didn't notice him, he noticed me. Do you think he did all this just to make fun of me? Or does he actually have feelings for me?