I read the article and felt sad. There's a lot of emotionally charged language (repeatedly: "I was a shitty husband"), but stripping away that language, his main point is consistent with his Atlantic article. Namely, that while he tried to be a good husband for the 'big issues' (e.g. never cheating), he was neglectful for the little things, and didn't give her enough attention or care.

My interpretation is that the divorce was somewhat unexpected as there were no major issues besides the 'little things,' but he largely feels that the divorce was out of his locus of control. He's then compensating to assert that it really was in his control, and also severely criticizing himself with emotionally charged language for letting the divorce happen.

Given the information at the time, I don't think the divorce was avoidable. If anything, the ex-spouse at least has an iota responsibility to identify the feelings of neglect, rather than pointing out the neglectful habits without reflecting on why she was so bothered them.

It would be healthiest for him to let it go, and find happiness elsewhere in life (e.g. with another partner and pursuit) and move on as much as possible (though it's hard as he has a kid). It's hard to see him really make the divorce part of his identity, the point where he publishes a book about it, writes in The Atlantic, and even offers divorce counseling services at the end.