The problem is, H thinks he is perfectly free to dither around in his indecision. He can spend the night with the OW, (and there's really no doubt that's where he was, is there?) and then come home to "compare" and see if he wants to stay or go - the power of decision is all his. If, on the other hand, he sees that his W has a life, friends, and maybe, just maybe, there is a possibility SHE might meet someone new - that suddenly makes him realize that he might lose her. That the decision making might not all be in his hands. And believe me, even when they are sleeping with the OP, just the thought of the LBS in the arms of another can still drive them crazy.
Note that I am not advocating ACTUALLY dating - just giving the S the idea that it could happen. Also - the 180 of her not being the "boring responsible one" can be a good thing.
It's no coincidence that when the LBS finally gives up and moves on, the WAS often tries to come back. Isn't it better to trigger some of that jealousy now, before it's too late?
