What did I do?????????

Okay so this dude I like has a girlfriend. I know it's bad to like him.but when he gets in fights with his girlfriend he always will stare at me and wont look away. but when they make up he rarely will look at me. He already knows I've liked him.he never said I was ugly or pretty he just said he could t say because he has a girlfriend. Okay so I messaged him the other day and said hi and he never responded I know he's been online.my friend said hi.and he said hi.what did I do?like is it hard for him to say hi...please tell me wat u think about this.