eav, you make an interesting point about the percentage of affair marriages.
My understanding is that the 2-3% figure comes from the concatenation of two other figures: The number of affairs that lead to divorce, and the number that then go on and lead to marriage.
If I recall correctly, each of those numbers is in the 10-15% range. So: 10-15% of affairs outlast the marriage. Of those, 10-15% lead to a marriage that lasts more than 5 years. (That's how they define a "successful" marriage in the research, don't ask me why.)
If you think about folks who find and then stay on MB, they're often the ones where the affair doesn't die immediately. I suspect that folks who post here are a little more likely to be the ones where the affair outlasts the marriage.
And the second figure? Well, a lot of the marriages where the ex married the affair partner are a good bit younger than five years old -- there aren't a whole lot of posters from before 2001, though there are some.
So I suspect a lot of the relationships that started as affairs and have become marriages have not yet played out their full life-cycle. Many of these do end in divorce, whether it's in 5 years or 25 years. 65% of ALL second marriages end in divorce, after all, and the percentage is higher for affairs.
However, that does not mean that any one marriage that started as an affair will end. Nor, in my view, does it mean that they all SHOULD end. We've read several times about the circumstances under which the Harleys will help when a marriage began as an affair. I tend to agree with them that if there are children in the second marriage, and not the first, then the second marriage should be helped to survive. Similarly, if the former spouses want nothing to do with them, then lets give the new marriage support. I like that, too.
I would probably go a little further and try to provide help for figuring out the best approach (whether divorce or not) in situations where there are children from more than one marriage and partners in various states of wanting to reconcile or not. In my view, the "greater good" in each of these situations may not mean rebuilding the first marriage. It's also the case, however, that these situations are rife with ethical and moral problems and dilemmas. There's no "clean" solution -- just less-bad alternatives and painful consequences no matter what you do.