I'm not the least offended, and I think you bring up many important (and valid) points. I'm sure many WAs are fleeing from their own demons, rather than their marriage and their spouses. I'd even agree that, to a point, differences can enhance a marriage.
On the other hand, some differences make it hard to maintain an involved marriage. The morning person/night person issue is, I do believe, a problematic one. How can you actively work on your marriage if you only see each other for half an hour each day? He'd ask her to stay up longer, so they could talk/watch tv together, but she said she needed her sleep. That left the weekends. But even there, finding things that both enjoyed was difficult. He told her he needed more physical affection (not just sex, but hugs, holding hands, etc) but she said she wasn't a touchy-feely person, and would never be.
If one person really enjoys dinner parties/social outings, and the other despises them? If one person loves spending hours on the computer, and the other won't touch them with a ten-foot-pole? (These are just random examples for many similar issues) If there is really nothing both like to do together, and everybody lives their own seperate lives, connected only through the mutual love for the children?
He never claimed any of this was her "fault", that she was a kind person, a loyal friend, and an excellent mother. That she had a right to be her own person, have her own preferences and pursue her own interests. He'd just come to the point where being physically present in the marriage without any emotional connection for the next twenty years seemed a dreary prospect, whereas she thought simply "having" a husband, a beautiful home, and three wonderful children was as perfect as it could be.
Let me reiterate that the situation as described above I got not only from him, but also from his children. I had a few very intense discussions with his D14, because I wanted her to be able to express her feelings, what pain, insecurities and confusion she might have, openly. She's a wonderful girl, and a tribute to her mother's parenting skills. During those discussion, the girl herself made many comments about her parent's marriage, even though I really just wanted to talk about "her". She pretty much painted the exact same picture of their household as her father - two loving parents living in different worlds. One particular comment was "I don't know what they were thinking when they got married - they are polar opposites in every way".
He didn't chose me because of sex, he chose me because we could talk. For hours, about life, politics, science, whatnot. To this day, she doesn't see that, thinks she had a great marriage, and that he left for a pretty face.
I hope I didn't offend you either, Wonder, and I can only imagine how painful your situation must be for you. One of the reasons I came to this site is that I wanted to see the LBSs perspective, and I've learned much from all of you. Each sitch is different, but I hope the insight into the WAs motivations and reasonings will prove to be helpful to you, too.
Please feel free to continue this conversation, and don't be afraid to ask hard questions. I think they could benefit me more than anyone.