It's done. I personally know a couple who've done this. They're "pillars of the community", but since the guy's straight-acting, not many people know his true leanings. His wife married him on the condition that he gave her a child, and was then allowed to follow her own life, unless to be seen with her husband at functions where it "looked better" to have them there as a couple. The woman has everything that money can buy, her own set of "friends", and the status of being married to this guy. According to IaP - she'd be a "beard"!
They certainly do - but she gets those catered fir, elsewhere! Seems a bit mercinary to me, but in way, she's not doing any harm to anyone. Her and her husband actually get on very well in private, but she turns a blind eye to what he gets up to, and it suits them both. They have a 16 year old daughter together, and her father loves her to bits. It all seems a bit irregular, but I guess that if everyone's happy with the situation, then there's far worse out there.