Years ago, I read a similiar article. It focused on child abuse. The number of times a single mother's boyfriend was the prep. in abusing/killing the child/children was horrifying. The article indicated that the real father of the children was much more likely to be a protection to the child than a boyfriend was, as the boyfriend was jealous of another man's kid.
It reminded me of a National Geographic Special that showed male lions killing the offspring of the previous alpha male when there was a pride takeover. The new alpha wanted his DNA spread, and not the predecessors, so he mauled the cubs to death.
There are many, many single mothers who work very hard to raise their kids.