Hendricks says, the deep purpose of our love relationships is to heal our childhood wounds and to grow beyond them. This is a profound insight. There are many factors. What people often do not realize, I think, is that a good marriage will require you to grow emotionally. If you are incapable of that, at some level it will not work.
Marriage challenges our capacity for emotional growth.
I am not sure it really is entirely a crap shoot. Success is not merely random. The more conscious and mature we are going into marriage, the better are our chances. And of course, compatibility matters. Simone de Beauvoir once observed that it made good sense to have a partner of youth and a different partner for the second half of life.