Mills & Boon--> romantic fiction <--- that's what monogamy and marriage is
Maybe you're right, but if someone says that they punt and still love their wife, why do you doubt them.
Are you calling them liars, without having any idea what their circumstances or reasons for punting are.
Why not just accept what they're saying.
You might not be able to imagine any such circumstances, or simply just choose to be critical of that concept, but why not just accept what they say.
Here's a few to consider:-
Open marriage,
Living apart for long periods,
Wife unable or unwilling to have sex,
Wife has chronic mental or physical illness, dementia, or in care,
Husband is addicted to sex, or simply unable to get the sexual satisfaction from the relationship.
And I'm sure there's many more.
These sort of circumstances may occur more often, but not exclusively with older couples.
There's a discussion on why you hate your wife....... I'm just offering a balance.