Whats to say that he is just waiting for the kids to graduate to walk out the door?
That is very possible...beeing a child of parents who were going through their D as I was getting married I can tell you it probably would have been better if they had done it while I was young, it's not like I didn't see it coming anyway.
I have a question for you? Does he suffer from depression? I don't know if it's depression but he does seem to have anxiety issues and has been on meds for it off an on for the past few years.
What does he do when he gets home from work? Does he interacts with the kids when they ask him to play games with them or does he just blows them off?
He gets home, says hello to the dog, then the kids, then sits at the computer checking the weather or sports, takes a shower, eats (sometimes with us) then either goes to bed or to a couch to watch sports or news and falls asleep. The kids don't ask him to play because he just doesn't.