"Each for the other" - "A unity in two"
In God's plan man and woman have the vocation of "subduing" the earth as stewards of God. This sovereignty is not to be an arbitrary and destructive domination. God calls man and woman, made in the image of the Creator "who loves everything that exists", to share in his providence toward other creatures; hence their responsibility for the world God has entrusted to them.
Source: Catechism of the Catholic Church (Vatican.va)