Actually, I think you are thinking of Debra Winger. She did stay at the Governor's Mansion fairly frequently -- or at least there were rumors of that. IIRC, Kerrey and Winger met when she was doing the Terms of Endearment movie in Nebraska. Kerry got into a little bit of trouble by letting Winger drive the Governor's limo (owned by the taxpayers) around the state by herself.
Kerrey may have dated Ronstadt too, but I don't remember that.
You are right it was Winger who lived with Kerrey.
I believe that something happened with Ronstadt and Kerrey after she and Moonbeam floated apart.