Perhaps this is a really simplistic example, but when I sit on my couch, my dog will sometimes try to get her front paws on the couch so that she can get a better scratch behind the ears. As soon as she does, I stop scratching. She then steps back off the couch and I don't start scratching again until she does. Sometimes a lack of positive re-enforcement is enough to enforce a boundary. (Sometimes it isn't.)
It may work for a dog who has no visible alternatives, but when you are dealing with an addicted spouse who has a third party pressuring them to leave the marriage its a bit difficult.
You try getting your dog to cooperate when someone else they like even more is waving cookies at them... Go ahead, I dare you
