I've noticed that some LBS, particularly males, will do some trial and error flirting and even have lunch with a female. Their goal isn't to start a new relationship but rather test the waters to see if they are still in the running. They almost universally return with confidence and more energy to DB. If I wasn't living with my WH and allegedly piecing then I would give it a go. Human are usually very predictable and the walk-aways often get jealous and suddenly realize their spouses may not wait on them much longer.
I watched the LRT video and MWD mentions that a woman was texting a female friend about how excited she was to visit her friend and lots of effusive comments. Unbeknownst to her, her husband was able to view these conversations on an ipad and became jealous and suddenly engaged back into the marriage. I think walk-aways feel their spouse won't move on, won't be able to find someone else and that they can depend on their spouses for plan B. Surprise, surprise when they find that to be untrue.
M 10yrs T 13yrs BD #1Oct 2015-PA between WAH and COW BD #2 April 2016-WH resumed PA, she broke it off Jan 2 2017 WH says he wants divorce April '17-Letting go 2018 D busted DD8, DS6, DS3