I think a lot of it is self-esteem based. Back when I was childfree and dating, I had dealbreakers that included anyone with a messy car or home, any 'Mama's Boys', any man with kids, any who had an ex on the scene or referred to 'my psycho ex' or, further into the relationship, if I discovered he was being enabled in life by another adult and/or incapable of adulting, or who expected dinner on the table and all the lifework done by the woman, no matter how much I cared for them/liked them. That was like a bucket of ice water on my libido.
But a number of friends were incapable of staying single, were rescuers that felt needed by cases like this (when really, to men like this, women are replaceable as long as they enable him), or thought he'd change for them. And years later, are either stuck with a selfish, lazy minger, or divorced.
It's important to try to recognise the signs, learn to recognise the signs, when possible.
I've certainly fallen for it, the love-bombing guy who later on tells you he's 'old-fashioned' and bangs on about everyone 'earning their crust' is telling you he expects a flatmate who will work FT and split it all 50/50, but one he can fuck and who will also cook his dinner and wash his socks.
The other issue is that when you find yourself with one of these specimens, and you've already procreated with him and you want another child, depending on your age and financial status, a lot of women go ahead and have another with him as it's convenient.
Prevention is easier than cure so teaching our children to value themselves and their own company, to not be sexist, to spot a sexist and to remember that if you don't love yourself first, then no one will ever truly be able to love you because love is respect, to be financially prudent and make sound financial decisions and/or seek impartial help before making big financial moves (even on forums like this, moneysavingexpert and the like) goes a long way.