Help! Guy in a relationship likes me, I like him too

So im in my first year of college and I went in with the main focus of school work comes first. All throughout high school I was looking and looking for a relationship but im picky and no one was good enough. Now that im in college I stopped looking because I didnt want to get distracted. Its funny how when youre not looking for a guy you find one and it hits you like a truck. Me and this guy have this amazing connection. Hes the one ive been looking for, but it became clear he has a girlfriend. Im VERY against cheating and would never try to pull something on him but I can tell hes starting to like me and he tries to deny it and so do I which makes it worse. He gets frustrated and I can see it in his face. As time goes by he stares at me more and laughs with me more and more. We havent done anything wrong because we both are decent human beings and are keeping it friendly. Hes been with his girlfriend for 3 years and loves her but he likes me too. His girlfriend is starting to notice. What do I do in this situation? I have never felt like this before with someone so how can I just let that go? Do I let go? Or try harder to be with him? No matter what someone is gonna get hurt & this sucks.