You give her an ultimatum

You and Kristen have been dating for the past four years. You know that your girlfriends have had bad luck in keeping their clothes on in the past, but that was way back in your teens and early twenties, including when you first met Kristen.

As you and she have matured, however, you start believing that you bad luck has faded, and that now Kristen is just conveniently losing her clothes and getting naked all the time on purpose, out of habit from the good old days.

You've been meaning to pop her the question for a while, but you're afraid that with her attitude she might end up naked on your wedding day! You blush at the prospect of having a naked wife, so you've been putting the proposal off.

One day, however, you come up with an idea and call Kristen into the living room.

"Hey, honey," you broach the topic, "I've been thinking a lot about ... us."

"Yeah?" she asks, perking up in excitement.

"And I want to take this to the next level..."

"You do?" she keeps jazzing herself up.

"But there's that problem with you keeping your clothes..."

"John," she snaps, "we've been over this. That bad luck is because of you. I never had any troubles before I started dating you, so don't get mad at me."

"Right," you continue, "well, that was back when I was younger, and now I'm getting the feeling that you're just using that as an excuse to justify your nudity - maybe out of laziness, out of habit, maybe even out of exhibitionism, who knows. But I'm kind of tired of it, and I want to propose something to you."

"Go on," Kristen is hesitant.

"Well," you continue, "I want to give you a ring, but I need to make sure you won't end up as my naked wife. So, for the next six months you have a three-strikes rule for your nudity. Every time you're naked in public counts as a strike, and if you get three strikes, or are doing this on purpose, you're out and I'm breaking up with you. If you make it, though, I'll give you the ring of your dreams and we'll be engaged. How does that sound, dear?"