Kids are hard and time is cruel. My oldest will remember his grandparents, my youngest will barely remember his grandmother as an old lady who couldn’t talk right. Where my wife bounced back from the first child, it was a lot harder seven years later with the second.
Just having the energy and stamina to keep up with your kids is hard, gets harder as your body slows down, and gets really hard when your parents get older and have their own health problems. My mother-in-law went from being able watch the kids when we needed to, to no longer being able to drive because of a stroke and needing to be taken to therapy three times a week.