This is the another consequence of the 1950’s version of the American dream. Single income family brought home by the husband where the wife stayed home to raise children. Husband needed someone to tend to the house and the wife needed someone to support her. Marriage was imperative for both sexes to participate within society even if you hated your spouse. Kids grow up and move out and then BOOM(er) divorce.
Now that a single income household for a family is almost unheard of people don’t get married just for the money so later divorce is much less likely