Is it okay to like a guy even though he has a girlfriend?

i really like this guy, but he has a girlfriend. we're partners in a cl at school, and he always starts conversations with me. it's not like we 'flirt' but he has teased me a few times, and we have nice conversations. i think he's just friendly, though. but i on the other hand am falling head over heels for him, and its not even funny. but sometimes he does things that makes me think he might like me. like he randomly turns around and just smiles at me in the sweetest way. i definitely felt a 'connection' there. i am soo infatuated all day long just thinking about him, and i know it's not right, because he already has a girl in his life. i want to keep getting to know him, though. is that wrong? what would you do in my situation?