she hadn’t made him happy
I don't understand this argument at all. Not withstanding the fact that 'she' (wife) obviously 'made him happy' enough for him to MARRY her, and have children with her. Why is the onus on HER to make him happy? Maybe he didn't make HER happy, ever thought about that? But the difference was she believed in her vows, the promises she made to him and didn't decide to look for 'something new' and believed in making marriage work? We all have responsibility for our own happiness to a certain extent.
And if someone makes you happy enough that you choose to marry them and promise to be with the forever, til death do you part, but no longer does make you happy, then maybe you should try communicating and/or counselling. How about that as an idea, instead of what is more likely to be the case - to get 'bored', and move onto someone new for the excitement?
Why is it the wife's responsibility to make him happy, why isn't it their joint responsibility to make each other happy and stick to the promises that they made each other? They certainly made each other happy then! Marriage is excuse my language, fucking hard work! If you just want to sit back, let someone else make you happy and give up when you're bored, then you'll never be truly happy, you'll continue to chase an illusion of happiness. Sorry, but it would not surprise me if he wasn't at least a little unhappy even now. I think OWs delude themselves into thinking the man being unhappy was his exe's fault, and they can make him happy when his ex can't. Happiness is an internal state of being, and I do not believe someone who can be happy enough to propose/marry a person for the rest of their life can suddenly become unhappy and the OW make him happy. Nope. Delusional. He will be checking others others out, and he will eventually leave you, too. But not before he has someone lined up.
The narrative will then be the same 'she didn't make me happy'. OW are fools and get what they deserve eventually. Same goes for OM of course.