Why do you think most WW's are unhappy - or don't they know?
Not sure if this is just for sandi or not, but here's my quick thoughts on it:
Guilt/Shame, breaking up of a family/children, Feelings of Desperation (became wayward because was missing something). She might get a "fix", but no one likes feeling desperate, She's probably Lying a lot - losing touch with her real self in the process. She's disconnected from her authenticity... If there was codependency in the relationship, it's a new learning process without it. She's lost herself, her purpose, her passion, her everything, and she's only finding temporary fixes in whatever ways she can to fill the voids, only to end up back at the same place of sadness/regret/anger/despair...
I didn't put a lot of time into this, literally just what rolled off my fingers as I typed. but I think each case will be different, and really, if you know your W, the one that you married, not the one that's Wayward, it shouldn't be hard to diagnose the psychology issues she might be dealing with in leaving the M.