Coupling, Series Three

Susan:
I'd like to think that the man I'm going to spend the rest of my life with has a better reason for staying faithful than, "It might be a trick."

Steve:
Well, it wasn't the only thing! It was just like the... deterrent.

Susan:
The deterrent?

Steve:
Well, yeah. You know, like nuclear weaponry. I mean, nobody likes it, but it can help to keep the peace.

Susan:
Steve, you've just compared our relationship to the Cold War.

Steve:
Which, may I remind you, really lasted.

Susan:
So the nature of the bond between us is, in fact, the threat of mutually assured destruction?

Steve:
Oh, among many other things.