Acoording to MLCers who are able to remember and verbalize their feelings, they all say they missed their wives and families every single day. They all say they never stopped loving their spouse.... I suspect they forget the early times when their feelings were displaced and the drama of the affair made them feel "alive" again... that's how my husband describes it.
When they try and return, it is a deep desire to escape the affair R which is probably volatile on a good day.... it is exhausting and toxic and chokes the life out of them... the same way any addiction will. They "love" their spouse, but are pretty distracted.... it's not a romance novel where they suddenly say "OMG, I love you forever and will NEVER leave you...." they're still working the details out.
Of the stories I've heard, once they are over the alienator, it's as if they never existed... Stayed's husband felt guilty that he lived with his OW for a year, yet felt absolutely nothing for her once he was OVER it... it ran it's course and he gained strength to end it when he thought he was losing Stayed. I think they can feel they are in danger of losing you even if you live together.... true detachment can be felt.... it's that "take it or leave it" attitude and they know the door is open, not only to come in, but you'll let them go as well and be just fine either way.
For me, a benefit of my husband's repeated failures at returning have bought me some FREEDOM when the real relationship is built.... he might try to go back to his controlling ways, but deep down he knows he will have to take me or leave me as I am... no more controlling sh**. It's a good thing... a silver lining perhaps!