I don't believe that America's new pop princess would agree to relegate herself to being a beard. Her high status means that she doesn't have to do that. Having said that the relationship was almost certainly phony. They may have liked each other but I doubt that there was any getting down and dirty!
You don't? Do you know about entertainment contracts?
Clue: they will do anything
to keep their star shining. Especially if there's mutual benefit.