Do you think that could at all be attributed that you are actually more alone now?
What I mean is, most families aren't interacting much with people outside their immediate family, whereas in the past the extended family was around and built a support system for those immediate families. If you had your parents, siblings, cousins, etc... around, you might actually have more time to recharge because child rearing wouldn't exclusively be put on the shoulders of the parents.
The way that our kids are raised now is incredibly different than the way I was raised. Although predominately raised by my parents, my grandparents, aunts, great aunts, etc... all had an influence and played a part in that upbringing due to the geographics of where everyone lived.