Remember that in this world a roman 20+ is already considered dated and husbands usually don't even look at them as woman anymore, and in this case specific Shizuko told that they are in a garbage marriage that the only function they have is to cook and help on the business, no love life or even care that they are.
So it's not rly a Cuck idea from us because this would be the case if they still loved the girl or something like this. They are just "well I don't rly care about her anymore, if you do and say u will treat her well, sure watever, be my guest", but I get it how weird it is because the setting is quite complciated because the morals are all twisted with this idea that most ppl die around 40-50yo too.