There's studies of life satisfaction by age and how it is U shaped.
High when you are young, high when you are old, and low in the middle 30s~50ish.
However for women, the later years life satisfaction never catches up to men.
Caring for both kids, parents, and eventually your own husband are huge factors here.
As people live longer, and children manage to remain under the partial care of their parents longer, the miserable middle age gets longer and more miserable.
I was remarking to my wife how, due to the wide age range of my siblings, my parents were dealing with children in the home & mothers in declining health for a total of 32 years! For 10 of those years they were dealing with BOTH kids at home & 1-2 mothers in declining health. With children & mothers spread across up to 5 states.
Suddenly at age 60 they found themselves empty nested & without parents to care for either.
They are clearly much happier than they'd been in a long long time.
Right now they are in good health, but statistically it's the men whose health fails first, which would put my mom back in the caregiver stage for 1..2..10 more years, who knows.