Indeed marriage is one of the ways in which we are related to him. Such relationships of trust are gifts of grace. These covenant relationships are means by which our lives can be transformed. The Christian experience of marriage and the teaching of the church through the ages is that marriage is a means of grace like the sacraments of baptism and the Lord's supper. The covenant a man and woman make with each other is one of the ways in which people develop a relationship with God.
Marriage too is a sacramental means of grace.
Just as God takes the ordinary food and drink brought to the Lord's Table and gives himself to us as heavenly food for our pilgrimage to eternal life, so too he takes the ordinary stuff of human relationships and through them relates himself to us. Yet, though marriage has a heavenly purpose, it is very definitely part of our life in the earth. So they are no longer two, but one flesh. It is part of God's plan and purpose in creation. It is a gift of God for a purpose.