The problem with this one AF is that it is not immaterial to Armbow's recovery. And all the while she is thinking that he is a nice kind man who fell out of love, she is vulnerable to him changing his mind again and then jumping through even more hoops trying to be the perfect wife.
Unlike SGB (and I suspect we will never agree with eachother on this SGB) I think there is a world of difference between someone who is leaving their marriage because it has run its course without outside interference - and the person who leaves because they have developed "feelings" for someone else.
The trouble with this is that there seems to be a whole army of romantic idiots out there at the moment (male and female) who are convincing themselves that their marriages must be doomed because they've developed "feelings" for someone else. From what I remember about your original thread armbow your H acted like a horrified priest when he realised he had a perfectly normal crush on a work colleague, instead of a more grown-up, pragmatic response which is that these things happen.
What I suspect happened then was that he had such an immature, romantic response to those feelings, that he started re-writing history and convincing himself that he had been unhappy for some time, because after all, that would explain why he has these feelings for someone else, wouldn't it? Of course this is nonsense. He's just a normal person, capable of making a connection with someone else and feeling a bit of sexual chemistry. It can happen to anyone if they are not careful - but self-aware people recognise it and deal with it, acknowledging too that they are now finding faults in their partner that didn't exist before.
In many ways, your H sounds like a pompous and self-righteous prig armbow, pretending that he is somehow "other wordly" and immune to the flaws that beset "other men".
If SGB is right though and it turns out that he has left your marriage because he has developed feelings for someone else, then it would still be better that he was honest with you. It will give you a kind of closure, I think.