Yeah. I selected a few of the volume descriptions to abstract the principles he was trying to communicate.
Overall, it sounds like the divorce was unexpected and out of his control, so he's trying to reassert control by nitpicking his faults and using emotionally charged, self-critical language ("I was a shitty husband").
Some make sense (and all likely contributed). However, Vol. 9 and 11 were strong indications that that there were broader issues than neglect. In specific for Vol. 9, his spouse wasn't willing to respect his want for alone time, implying a compatibility issue.
-Vol. 3, don't be neglectful to your spouse at a party: "I was at a party and I had a tiny crush on the married birthday girl, and I watched her husband ignore her all night (and already knew him to be a less-than-ideal partner). The whole scene made me sad because it reminded me of how I used to treat my ex-wife."
-Vol. 6, remove some of the burden of decision-making: "You can destroy your marriage by trying to be “nice.” By letting your spouse make all the decisions. You think it’s a nice gesture, letting the other person have their way"
-Vol. 8, don't roast/mock your partner so much: "What starts at an early age on playgrounds, turns into a relationship killer in adulthood. Men using jokes, sarcasm and mockery to belittle their wives and girlfriends both privately and publicly."
-Vol. 9, wanting alone time is neglectful (I disagree and don't think it's a "guy" thing; it's very possible to be in a relationship with an introvert who gets the need for alone time): "Guys like “Me”-time. Maybe everyone does. But a lot of time when husbands and fathers do it, it looks and feels to his wife and children like he isn’t interested in them or that he’d rather spend time alone than with his family. "
-Vol. 11, fixing a marriage is about working on yourself (it's plausible, but it sounds one-sided): "I think married couples who are sad and angry about their lives and relationships make the mistake of trying to “fix the marriage.” They spend all their time trying to figure out how “we” can do things different, and how the other person can make changes to make life better. But I think people need to work on themselves to fix the marriage. To look inside themselves and figure out how they can be their best self."
General neglect was a major driver, but there were other bigger issues. The lack of respect by his spouse for his alone time is a major one, like in the full Vol. 1 article [0], where he says a major failure was choosing to see a televised once-a-year major golf tournament instead of going for a picnic in a park because she loves the outdoors.
If he actually skipped the tournament to go out, it's also likely he would have become resentful (even if he had the best intentions); bottled up, this can cause issues down the road. On the other hand, his spouse ended up as a person who was resentful, which did lead to issues down the road. He suggests the solution was to suppress his own wants, but a better solution would be to find some way to compromise, because both wants are important.
It's also concerning that he's then offering paid divorce/marriage counselling, when I don't think he's qualified (to his own admission of lack of formal credentials).
[0] https://matthewfray.com/2013/07/03/an-open-letter-to-shitty-...