I read Greenblue's comment also, but I don't think the intention was quite as you interpreted it... though, that's how I read it first also. Maybe "cemented" isn't the right term... it's that the WAW has these big decision points where life smacks them in the face. They can push stuff to the side, but when that moment comes they have to face it. Telling the kids, filing D, moving out, signing a lease, etc...
Once they pass this milestone they aren't cemented in their new life, they've simply gone past a hurdle. If the new life is rosy and cheery and all they hoped it would be then why would they return? But if the new life isn't all it's cracked up to be, then it gives them a reason to reconsider. That's where the road home being paved and smooth is important.
FWIW it's one of the reasons I've insisted on buying the house from my W. It's large enough for our family. If I was living in a small apartment and my W is living in a small house and she wanted to return, it's one less reason against it. We fit the family in here before we know it works
Married 6 together 8 Me:38 W:31 second marriage for both SS12, SD10, S6 Bomb: 9/8/11 (day before our 5 yr ann) W moved out: 2/18/12 D final: 11/12/12 Share S 50/50. Spend as much time as I can with SS & SD