Has she ever chewed up something your fiancee liked? I'm just wondering cause I know with Baloo my hubby wouldn't tell the puppy to stop chewing at first until he tried going after the tv speakers...hubby did a complete 180. And like others have suggested I would confine them until they've mastered what it means to be a good dog within that one room and then expand their surroundings. We're having the same problem with Baloo being able to climb out of his x-pen and over baby gates, so we're getting a top cover for the x-pen shortly.
I hope you figure out a solution cause I'm sure in 3 months or so Baloo will be going through the same thing and I'll be posting asking all sorts of questions on how to fix it!!
Goodluck!