People don't have enough experience, they get married too early, without having lived enough time together.
Not really true in my opinion about people having to live together enough time before having to get married if they're compatible.
By coming from a home where you have your father and mother treat eachother right and with love and respect the children get to pick those experiences and grow with it as they get to grow from a loving home. A lot of trouble couples happened to be persons who grew up from a violent experienced parenting scenes where the home was truly a home and this has to affect their behaviour when they grow up and get married.