The Root Cause of All Marriage Problems I can tell you without any fear of contradiction or oversimplification that the root cause of all marriage conflicts is selfishness. I can say that because there’s probably no better practical synonym for the concept of sin than selfishness. Sin (i.e., selfishness) is at the heart of all marriage problems. Now obviously, just as our “love is giving” definition was deficient because it was too limited in scope, so “sin is selfishness” is too narrow to be theologically