It is super common at D’s school to give couples a couple of hours alone in the room and then have the bf/gf sleep over on a futon or something. One of my d’s roommates last year had a bf who was there more than 50% of the time. The other girls thought he was super and included him in their secret santa exchange and jokingly referred to him as the 5th roommate. It doesn’t have to be such a big deal.