^
That's true. But my folks were married at 19/20 (respectively), had no problems in their marriage and they're mid 50's now. Grandparents all married when they were 17-18 too and they're all still together.
It's was a different time in your grandparents day. People were expected to make marriage work. And as I'm only a couple years younger than your parents, I can say the same thing was true as well, though in this day and age, its easier, with Hollywood's example, to just divorce and move on to the next in line.