“There’s probably a whole lot more to the story.
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It may have to do with Trig.
Sometimes when there is a disabled child in the mix, the mother tends to forget she’s a wife/mate/sexual partner.
If the husband cannot break through the thinking mode which the wife is in the marriage cannot make it.
She could truly think all is good and not see the issues.
If he’s already filed though, he’s already moved on, which is a shame. For both of them and the family.
It may have to do with the child; but everything you wrote could equally apply to the effect of sudden national fame/notoriety and all the crap that went along with it.
(Even winning the lottery in a big way, has destroyed - or changed drastically the dynamics - of marriages and family relations.)