fauxhabitator

One who rents a residence with roommates and yet spends all their time at a lover's residence instead. The place is only rented for rationalization, to take the pressure off the relationship and to keep parents from getting mad at you for "living in sin."

"The place is sweet. It's got a huge living room, perfect for parties, and my roommate's a fauxhabitator so I got the place to myself!"