Will adult children look after an elderly step-parent with the same devotion they would show a parent?
This is a sad trend of divorce being so common.
I thik people's expecations of what marriage is and what marriage should be has changed. Divorce was once a last resort, or shameful, now it's no big deal.
But then again, close families like "The Waltons" were not common even in the old days. In so many families, people don't get along, or do something to cause family rifts. That was true in the old days and still true today. So as far as having family to take care of you in your old age, that was always problematical.