It’s not uncommon for Universities to restrict housing to members of the same sex in a given domicile. This prevents a number of tricky issues that would be likely to crop up otherwise (couple breaks up – who gets the room? parents of a student don’t approve of a living situation – how does the University handle that since most students here are legal adults? domestic violence problems could be exacerbated, etc.). Yes, it mostly assumes that everyone has “traditional” views on relationships, but it is successful in handling most of these potential problems.