You Cheated? After We AGREED?

OverLawyered has this to say about relationship exclusivity contracts (HT: ATL):

I have often wondered if, were courts to fully embrace contract marriage, they might also recognize a status short of it: something akin to a relationship contract. That’s the issue facing an Illinois court right now, as Nicole Basarich is suing Robert Lane, with whom she cohabitated for more than sixteen years, for “violating the[ir] agreement for an exclusive relationship” and for failing to pay his portion of the mortgage. Forget the latter claim: I’m fascinated by the former.

I've never wondered that (and I take that to be a good sign), but now I'm fascinated, too . . . one argument suggests that such a contract would be against social policy. But wouldn't that apply to marriage, as well?