UnconditionalLove, I will add my story, the short version, for your discussion thread.
My xH's love affair was started by him, not by her directly. The OW is xH's old high school GF from 1976-77...she broke it off after my H went into the army and married another HS guy shortly thereafter. That M lasted 3 years or so and she has been single since then and has no children...totally available. They are both 56 years old now, I am 58 yo. H and I met in early 1993 and married in mid 1994. He had no contact with her for all that time in-between and didn't want to as she had broken his heart in 1977.
In Jan. 2010, the OW came to town (from south US to north US) to visit her father in the hospital and stopped by H's parents house for a visit and said to tell Mr. OL that she said hello. His sis did tell him this info; his mother said that she would not. A few weeks later, H found her info thru the internet and called her on Valentine's Day for a 10 minute conversation on his way home from work. I looked at the phone calls a few months later and found this out. During that time the phone calls were 3 or 4 hours per day as well as ipod texting while he was home. 4 weeks after the start of the EA and never seeing her yet, he asked for a divorce while prancing around the kitchen ...very unusual for him to be acting like that or talking about a D. 4 weeks after that he filed for the D without me knowing it, 2.5 months later he left our home after the intimacy had increased from Zero to full-on (his idea, I was very confused by this), and 3 years later the D was final, including 1 year for the state supreme court appeal which H filed for. The OW moved here 2 months after H moved out but to a different town than he or I...her plan all along I think.
I don't know much about their R but 6 months after he left, he said that they would never live together....I guess there was a problem there...or so it seemed that day. I know there were a few times when they were fighting and he was the one to call and reconnect (emotionally needy). I have seen emails where she was telling him what to do during the D and with our taxes...and it was not good news for me. MLCer's cannot think straight and they do what the OW tells them to do. After ~4.75 years, they have never lived together, but she is still the OW.
My S15, now S18, lived with him for 3.5 years until 1 month ago when he went off to tech school a few states away. He told me that xH threw her out of the house and his parents house on 2 occasions as OW and S18 do not get alone at all and were fighting. xH's family was very surprised at that! (Yes, his family has believed all of his lies and half truths about his terrible wifey!) XH moved 2 weeks after S18 left (free now) and I do not know where he went; I do not know for sure if they are living together now or not....my S18 says he doesn't think so. I do know (from S18) that he has moved to a part of the state that he would never go to before to be closer to OW's place. So, now that he is free of any responsibility to his family, we will see what happens. I think he has been in Limbo for 3.5 years while S was living with him, although he went to OW's place every weekend and left S to fend for himself. Last summer I got an email from xH stating that he wanted to 'get past our recent history' but he has said nothing else since that time....maybe he forgot. LOL He does not talk to me and has been that way for many years...he will occasionally answer an email but only about S18, nothing about himself. S18 lived with his father for all that time but they never did anything together or hardly spoke...only about cars at S18's probing. OW was his complete distraction from life and family. I do not know which one of them is more manipulative, xH or OW but, I do not see it as a very healthy relationship...just a needy one on both parts. I think that the infatuation has worn off but xH has done much harm and I do not believe that he knows how to or wants to fix anything; narcissists do not apologize for their mistakes...as they have none!! He is still very lost after all this time! He was withdrawn from S and I for many years before he called the OW...early Separation and low-level depression I suppose.
Well, that is the short story. I don't know if it answered any of your Q's or not but I don't think all is swell in MLC land!
And, YES....she was the first one to come along and pay him any attention. I believe that he would still be home if she had told him, a married man, to go away....but, she told him that leaving him was the worse mistake of her life and that he should divorce his wife to be with her....so he did!!!