Most Helpful Girl
From what I've seen, it's couples have a seriously different value or desire for the relationship that they don't confront before getting married.
Where to live
Drinking or drug use
How to raise kids
Priorities for money or free time
How you treat a partner & express love
They either don't discuss or more commonly think it'll all just magically work out. When that doesn't happen, they think kids will help, which compounds the issue.