Sharing 600 square-feet with another person is humiliating enough. Don't degrade your roommate further by forcing a permanent, rent-free house guest into the apartment. A live-in girlfriend carries all the potential pitfalls of another roommate, with the added drawback of having to hold your farts in. Also, having your television held captive by Bravo. So, unless you want your roommate to suffer a collapsed anus during a rerun of Millionaire Matchmaker, you'd be wise to hold on to your extra set of keys.