[auctiontheory]

If almost 45% of San Franciscans are single, plus a chunk of polyamorous, co-opers, and goodness knows who else, it may not be true that "most people live in couples." http://www.bestplaces.net/docs/studies/solocities.aspx

Also, I know it's often done, but a one-bedroom is rather cozy for two people for the long term.