@Itsn
It's voluntary though.
For situations like this try and flip the gender. Two girls a guy's in a relationship with violently abuse him, but he's with them out his own volition. He's cheating on both of them, has a kid with one and has the other raise it.
There's a word for girls who try to find unappealing guys to raise their children while they actually have the kid with someone else. I forgot the word for it though. It's a female trait that exists in all mammals.
Found the word. Hypergamy.