Is she single, interested, or taken?

Theres a girl at my lunch who stares at me but quickly looks away when I look at her. In her lunch group she always sits next to the same guy and I cant tell if their a couple. She seems interested in me but I cant approach her because I feel like the guy she sits with might be her boyfriend. I also dont want to stalk her outside of the cafeteria to find out because I dont want to come off creepy or get beat up by the guy. I like her but shes a senior and Im a junior and I don't know if it will work out. I dont know what to do. Im scared the guy will find out and beat me up. Were about the same height, have a lot of the same features, except he has like 50lbs on me. I dont think I would put up much of a fight. I think shes attracted to both of us because of our similar features however hes more of an alpha male and Im more of an average joe. I dont think I have a chance. I feel like any angle I come at this it will end bad for me. Should I let it go? What should I do?