Just found this thread and I'm in newcomers myself. I have thought my W was having a MLC since this nightmare begun and in hindsight it probably started more like 12-18 months ago.
I had a thought last night of the difference between a WAS and a MLC (although a lot of similarities). A WAS does not always do the stuff of a MLC's, they have just had enough and want out of the relationship whereas a MLC will be acting like a hormonal teenager. They have no cares for anyone else but themselves with what they are doing and cannot be rational about anything.
Anyway, as to the point in question. I've spoken to a few people who've been through D and they do tend to have regrets. Even those in happy new R, but with kids say they wouldn't want to go through that again or put anyone through that.
A lot of people I also notice, will love the single going out life for a while, then the monotony will set in and they would prefer some more nights at home cuddled up to someone they love etc.
I'm 100% sure my W will have regrets, I've not heard one person that know's both of us not be shocked by what she is doing and/or not called her mad. The only people that are are the small group of new friends that don't know me at all and want their wild drinking buddy to party with. I do not believe my W would ever admit it tho as she is the most stubborn person in the world (her dad is close, and may actually win that one to be fair) and I feel we will be divorced inside 12 months.