Guys, what's your opinions about this? Shall i mind??

The guy that I like is a foreign student. He used to rent a room with his brother but now that his brother moves out to live elsewhere, he is looking for another roommate. In their rented house, there are other roommates, and some of them are female, but i don't mind as long as they don't share the same room. I was kinda worried that he may look for a roommate who's a female and they will share the room, and since he's unattached and never had any relationships, I don't know what may happen to them. I admit I am being jealous and I hope he stays "pure" and lives with a same roommate. I asked him indirectly, that if he mind if the roommate is a girl, he said he don't mind at all, as long as he can share the cost with someone. But i don't think things are that easy, so i kind of told him that he should avoid the roommate of the opposite and he wasn't very happy about it. What should i do? Shall i mind if they really live together?