[nah]

Is that why they vanish so the truth about them does not come out.  So that one does not call them out for playing a role?

My best guess from putting together what came out of the mouth of The Leaver himself:

When asked from a good friend why The Leaver would move in with the girl after he said she was controlling and difficult, "I don't like to be alone"

Two years later while he was explaining why I needed to accept that he was different now (even though we hadn't talked in years), "I'm only happy when I'm alone in the woods with my dogs"

So I believe they vanish and hook up with someone who will accept anything is their way of being alone without really being alone.

Depressed people often describe feeling alone even when in a crowded room.  Easier to do with an other woman so they can change their personality without being noticed, they can't do that with us.

[living with Hope]

I believe that is when he became a vanisher when he knew that he was definitaly not going to be alone. 

[Treasur]

I think they run and find new scaffolding, a new picture of themselves with OW/OM as a mirror and no-one to point out, like the Emperor's New Clothes fairy tale, that they are actually (metaphorically) naked 

[Shocked]

I think they vanish because they think they are too good for the old life. It’s a quest to be the stud they want or imagine themselves to be. In the new person they get involved with they can be new persona without questions. No accountability. In mine’s case I think he was looking to find a drinking partner. No fun to drink alone. Getting drunk and being a big spender made him feel like a big shot.

[living with Hope]

I have struggled more internally with the vanishing than I did his coming and going.   What you said Shocked hit home in the sense that I often wonder why I was not good enough. 

And maybe it was that simple, he thought he was too good.

[nah]

Please don't be fooled with the we were not good enough monkey braining.

They left bc they were looking for someone worse than themselves.

[ChrissYAH]

I understand all that Nah but even to the point of marrying an ugly troll?? to the point of not caring if they never see or speak to their kids again?

[ChrissYAH]

Please don't be fooled with the we were not good enough monkey braining.

They left bc they were looking for someone worse than themselves.

Well HE told me i 'deserve better' and bloody oath I DO!

[living with Hope]

When people say he left you. He moved on. He is happy... 

I smile, I nod. or I just stare blankly thinking to myself "I hope you never have to walk this path."

If he did just leave me and move on and is happy (which I actually believe they have to be on some level to continue this life like they do), then why did he abandon his children in every sense of the word.

This is not normal behaviour.  If I bring it up to these well meaning people and their comments, they usually stare wide eyed back at me, not knowing how to answer.  Because no man or woman with a good heart or sane mind destroys their children in their own quest for happiness. Most people want better for their children than they had.    I know mine did before he ran away and hid his life for years . 

[ChrissYAH]

LWH

I agree with everything you have said, X justifies his actions by telling everyone the kids are old enough, has no contact with them because they won't accept his new 'wifey'