the right thing to do would be to ask him, but as the situation is a bit complicated... if something typical about homosexuality comes up, see how he reacts... sometimes, even if he is gay, as it is not accepted there, he may deny it or even act more negatively.try to form a friendship with him and get close, the closer you get the more intimate you'll be and then it'll be easier to discuss certain subjects and he might end up giving you some information. Many gay men fall in love with heterosexuals and become desperate for that man's attention, I recommend, even if you don't know his sexual orientation yet, don't delude yourself because sometimes he can't even be one and that can end up breaking your heart...be patient