1.Children add stress to a marriage and that marital satisfaction decreases sharply when kids become part of the relationship. Interestingly, this also happens to unmarried couples, so marriage itself is not the culprit in relationships that go stale.
2. Children create stress for parents as individuals, as well as the couple as a unit. Perhaps not surprisingly, mothers take on the lion's share of childcare in most relationships. Also not surprisingly, this stress hits mothers in particular pretty hard. Most women's other relationships deteriorate to a degree as their bond with their children grows stronger.
3. The stress of children is universal.It's not isolated to certain social classes or even to specific countries or regions of the world.