Permanence is intrinsically linked to faithfulness. To be faithful forever implies the marriage is forever. It is the promise of faithfulness that demands that any married couple, when the marital relationship begins to die, seek appropriate counseling to help them grow more deeply into their union. Those who come to the Church for marriage also promise each other a conjugal life and the right to have children. That means that sexuality is a necessity in a marital relationship.
Sexuality is a sign of the whole person in the unity of love.
Children that flow from this unity are living signs of what a couple is for one another. Husband and wife may choose not to have any children, but they must make that commitment as one. Each has the right to children if that is indeed what either may really want. All of those spoken and written promises come together in the midst of the Church, the People of God, and the presence of Jesus Christ Himself. The Christian community is the Body of Christ.