Here is a new film, a documentary, being made by a friend of a friend.
It's called "Apartners" which I believe is also a new term for it. She says on her film site that 25% of all couples in North America have their own room (common) and that 10% of all couples in North America prefer to live apart (that's the old gayer stats no? Maybe more will come out!)
Anyway, here's a link to her film website
http://apartnersthemovie.com/HOME.html