3 of my teachers are married to people they dated in highschool
I see your anecdote and raise you this:
Most of the adults in relationships I know either are not married to their high school sweet heart or previously were and divorced. The few that are still married would be better off getting divorced.
The ones not married/not married to their high school partner are in high paying, fulfilling, and successful careers while the ones who are aren't going anywhere in life.