I wouldn't be surprised.
I should clarify that (here in the States) three or more persons can share an apartment or dorm as roommates, without fear of intervention by the Law. Not sure how the Law distinguishes between that and some kind of romantic live-in situation, but maybe it has its own ways?
And has others have said, much of this (the non-live-in part) has to do with old anti-adultery laws that need to be removed from the books.
Love means never having to say, "Put down that meat cleaver!"