Guy I like Has a Gf!?

So theres this guy that works on my college campus, I work on campus too but at a bookstore so anyway I really like him. He would always come in the store to say hi to me before I liked him. I didn't know his name but he knew mine and that I was into art and stuff, which was weird cuz I didn't know him or remember ever talken to him bout it. Well steadily I started talken to him more like everyday and I really like him I guess the reason is is cuz he knew a lot about me and showed interest in me before I even knew his name! He would always ask me about my hair and how I did it and other stuff. Idk if hes just being nice maybe... but anyway like I said I really like him and I was asken him what he did over his weekend and what were his plans for the next weekend he said nothing and I asked him "really nothing? U have a girlfriend U not gonna hang with your her? and he was like no I gotta girlfriend but shes away right now" well I was kinda disappointed that he has one but I really really really like this guy. I asked my friends bout it they said so what? U could still be friends let him know im available if things don't work out between him and his girl. I mean I can deal with being good friends i still mite have a chance but still idk should I just forget him and not talk to him? or should I get to know him and build a great friendship?