It is when love is expressed in serving one another that the purpose of marriage is realised. In this sense marriage is the same as other aspects of life that can be made to serve God's purpose through faith and in the power of the Spirit. Both should serve each other, neither rules the other. Paul's word about not submitting again to slavery would apply here. But it is through the kind of love in which we gladly serve each other that both partners are fulfilled.
Faith is a relationship.
Paul put it in terms of knowledge. Our knowing God and his knowing us. Faith in Christ relates us to him. Indeed marriage is one of the ways in which we are related to him. Such relationships of trust are gifts of grace.