This is my analogy. I think it is easier for a person (mainly women) to commence another PA, if she has had previous partners before marriage. My W has only had me for 17 years, what do you think? Maybe I am being naive.
Don't mean to sound pessimistic or negative here, but I would think it would be more of a motivator than not. Please don't take me the wrong way, but what if in her mind, she thinks she's missed out on something? You know, the grass is greener on the other side BS!
My waw is involved with an ex-fiance from 15 years ago so my situation is a little different and probably less hopeful than yours since she's already experienced this Man and at one point wanted to marry him long before I came around. There is more to it than that, but it' s very complicated.
If I had my choice of which scenario I'd have a better chance of reconciliation with, I choose a OM that she has no history with.
"It is curious that physical courage should be so common in the world and moral courage so rare." -Mark Twain