I got home from my mission. I proposed marriage on our first date. Five children and 20 years (come September) later, we are happier than ever. Life has truly blessed us. You never know how it is going to work out and assuming that people are stupid for doing things like this is pointless. Time will prove to everyone whether their decision was a good one or not. My wife and I love each other dearly. Was it easy, absolutely not, but both of us were the types that are committed to what we do through thick and thin.
Now that my eldest was just sealed in the Logan temple to his wife, we are enjoying the next phase of our married life in preparation of the next generation to follow in a couple of years.
I think it is tragic to put a template or system of "this is how it is supposed to be" on dating, courting and getting married. I have seen so many marriages that sprung from longer term courtships end in divorce. The common denominator in most of these was "selfishness"
Give them a chance. They might shock you 40 years later when they are still happily married.