My boyfriend wants to live with another girl?

So Ive been dating my boyfriend for over a year now. I live in Ottawa and in September he went away to McGill for school. We've been doing really really well with the distance. He's been living in res but now he has to make plans about who he's going to live with next year. He wants to live with a girl. I really don't feel comfortable with this since a) I have nooo idea who she is and b) I feel like it's too intimate a thing to do when you're in a serious relationship. I've tried to explain to him how I feel and he really doesn't get it. If he does end up living with another girl I don't think I'll feel comfortable enough to keep dating him. I don't want it to come to that but I also don't want to give him any sort of ultimatum. Advice?