Relationship does not rescue us from our obligation to grow. On the contrary, marriage requires us to grow. We need to be ready for that challenge. It's a good thing marriage is fun too. Here's my list.
Compatibility is lucky.
It is also a willingness to do hard work and keep talking. Admitting our own shortcomings and an ability to forgive ourselves and each other. Obviously, love is important for marital success. Not just love as a feeling, but love as a habit, a spiritual discipline. There is a flow of love coming through us.