How do I know if he is gay?

I know this guy named Will Gilmore (the only reason why I am using his name is just incase he ever reads this, though unlikely) and I think I have been in love with him for the past year. we met at the begaining of the year and i though he was the biggest freshman ever, but he was a junior. we had great chemistry, at least that is what i though, but now we really don't see each other. the only problem is that i am gay and i don't know if he is. How do i know he he would ever feel the same? i just need to know or else he will be the "what if guy" in my life that i will always think about.