Why is that his wife's fault? No one has to do anything they don't want to do, but if he's feeling burned out and is realizing it's affecting not only his but her happiness too, it may be time to reassess. In relationships we become somewhat responsible for the other persons happiness too, and if he realizes what he's doing is messing with her too he needs to take a look at his life and decide what matters. Excuses can be found for anything but consciously choosing to neglect someone and then avoiding giving them any explanation for the behaviour is a dick move, regardless of the circumstances of your life.
I think you jump to conclusions because we've only heard half, her side of the story. I can't imagine someone like you would be fair and impartial if you were selected to serve on a Jury.
Their marriage is surely on a slippery slope.