Worth saying something?

Hey guys,So I'm a sophomore doing my undergrad and a few months ago I was assigned a grad student as a mentor from my college. I've never dated anyone and I've accepted that I'll probably be alone for a lot of my life... honestly it doesn't sound that bad. This is the first guy I've felt differently about and I'd give anything to be with him. He checks every box. I'm 75% sure he's straight but I honestly can't get a good read on him. He finishes grad school here in the spring and then he'll be moving to another country. My question is if it is even worth asking which way he swings? Even if he is into guys, is it responsible/fair to get into a relationship knowing that there is an expiration date that is fast approaching?