Walkingback, the Romantic Infidelity article mentions the affair partner having more problems than one can imagine and the unfaithful spouse going through some traumatic experiences. I believe this is what is happening in my sitch and it sounds exactly like your sitch.
If you haven't done so already, pick up Frank Pittman's book "Private Lies..." To paraphrase a chapter, "The affair will eventually end, and the aggrieved partner just might want to be nearby when that happens.”
Continue to attract, not to pursue. It sounds like the OW can be a downer, and your H may want to eventually want to hang out with someone more fun, like Walkingback!
