I think for me that DB'ing is about recapturing/rediscovering your authentic self (apologies if I sound too new age-y bc I am so NOT!)...
But I think by the time the bomb goes off a lot of us, me for sure, have spent so much time twisting and turning trying to meet the needs of our now-walk-aways that we aren't the people that we used to be, which happens to be the person our spouses fell in love with. Maybe it started out as us getting 'comfortable' with the idea that our spouse would always be there and we got complacent. Maybe, like me, having kids caused us to funnel more energy into the wee ones and less into our marriage.
At any rate, at some point our paths diverged. Then once we got a whiff of our spouse's unhappiness/discomfort/whatever, we tried to 'fix' things, appease, compromise, etc etc. I know before I found DB I was at a place where I was willing to settle for just about anything as long as he JUST DIDN'T LEAVE ME!!!
Wow, how appealing is that?
In fact once during a pleading session I suddenly saw how I must look and realized I was basically the shamed puppy (no offense Puppy!) showing my belly at my H's feet trying to earn his favor. Meanwhile he was 18 months into an affair...
But I digress. The point I am trying to make is that DBing helps take the focus OFF of the spouse and put it on you. Not so you can move on without them necessarily. But so you can remember just what it is you like to do, wear, eat, listen to, etc etc. And to remember that you are a whole person on your own, you don't need your spouse to complete you, they are there to complement you and vice versa.
Only when you recognize that you are a legitimate, worthy individual all on your own can you stand up for yourself and require respect from your spouse. And hold yourself to the expectations that come with a healthy relationship.
And at that point, when you have let them go live their fairy tale life and worked on healing yourself, that is when the WAS may look back to see why you aren't chasing them anymore. And they may (I say may because the WAS has the free will to just never look back even if we hate that thought) look back and see that a strong, desirable individual has replaced their clingy, distressed and depressed spouse.
That is when you are able to decide whether you want to give them another chance to rebuild your relationship. It is true, sometimes you look and see that they have not grown and are not a suitable mate at this time. But if they haven't done 'the work' that would be true whether or not you improved yourself.
So to me the options are, work on yourself and perhaps rebuild a new, improved relationship with a spouse willing to do the same; or, improve yourself, discover that your WAS just isn't making the effort, and be a healthier person to enter into a future, healthy relationship with someone else.
