How can I tell if he likes me in a romantic way or just as a friend?
I second everyone who says not to have a relationship with him unless you’re prepared to move out if it doesn’t go well, and only if it won’t freak out any other roommates. And, just to throw in a little more negativity, I don’t buy the, “oh, it’s a male fantasy to have some woman make the first move/jump him” stuff. That may be true, but my experience indicates that that doesn’t mean he wants to have a relationship afterwards. Go ahead and try if you want to, but frankly, the indicator of if he likes you in a romantic way, if he wants to date you, is that he asks you out. If he doesn’t, he won’t.
Use your friends! Do you have any that are close enough to him without making it obvious? For example, they can ask him if he likes these other girls who he knows. Chances are, that if he likes you, he’ll eventually let it slip he likes you. Or, mention in passing these other guys you know that you might consider dating. Pay attention to his vocal and visual cues. Does he tense up or get suddenly quiet? Yea, you could always ask him. Some people are mature enough to handle it if he doesn’t like you where nothing weird happens. Some aren’t. However, I dunno if I’d be willing to test that out by being forward about it, especially if you’re still living with him. Lastly, I know love is supposed to conquer all and most would say who cares, but also be considerate of your roommates. Would they freak out if you two started dating? If so, that can have seriously detrimental effects on the relationship if you two start dating.