Combined with a bias in family courts, an acceptance of alternate families (so a reduction in social costs of not marrying), and a rise in the acceptance of divorce. Why marry when you can cohabitate in a state without common law marriage. Having kids is still a challenge because if the couple splits custody still has to be decided, but there are a few options for that as well.

I'm sure that's what he's referring too.

Also the massive increase in hypergamy thanks to the commodification of dating.

You're not exempt from alimony or child support because you weren't married.