Divorce and social class
Commenters have been touting the extremely misleading statistic that early marriage has a higher likelihood of divorce, forgetting the rule not to confuse correlation with causation.
Higher social class people are less likely to get divorced. Higher social class people don’t marry before they are finished graduating from college, because it’s just not what their social class does.
Thus a marriage that takes place at an age prior to college graduation predicts low social class which in turn predicts a higher likelihood of divorce, but it’s not because they got married at an earlier age, it’s because they came from a bad pedigree in the first place.