Gaudium et Spes §49

⁴⁹ The biblical Word of God several times urges the betrothed and the married to nourish and develop their wedlock by pure conjugal love and undivided affection. Many men of our own age also highly regard true love between husband and wife as it manifests itself in a variety of ways depending on the worthy customs of various peoples and times. This love is an eminently human one since it is directed from one person to another through an affection of the will; it involves the good of the whole person, and therefore can enrich the expressions of body and mind with a unique dignity, ennobling these expressions as special ingredients and signs of the friendship distinctive of marriage. This love God has judged worthy of special gifts, healing, perfecting and exalting gifts of grace and of charity. Such love, merging the human with the divine, leads the spouses to a free and mutual gift of themselves, a gift providing itself by gentle affection and by deed, such love pervades the whole of their lives: indeed by its busy generosity it grows better and grows greater. Therefore it far excels mere erotic inclination, which, selfishly pursued, soon enough fades wretchedly away. This love is uniquely expressed and perfected through the appropriate enterprise of matrimony. The actions within marriage by which the couple are united intimately and chastely are noble and worthy ones. Expressed in a manner which is truly human, these actions promote that mutual self-giving by which spouses enrich each other with a joyful and a ready will. Sealed by mutual faithfulness and hallowed above all by Christ's sacrament, this love remains steadfastly true in body and in mind, in bright days or dark. It will never be profaned by adultery or divorce. Firmly established by the Lord, the unity of marriage will radiate from the equal personal dignity of wife and husband, a dignity acknowledged by mutual and total love. The constant fulfillment of the duties of this Christian vocation demands notable virtue. For this reason, strengthened by grace for holiness of life, the couple will painstakingly cultivate and pray for steadiness of love, large heartedness and the spirit of sacrifice. Authentic conjugal love will be more highly prized, and wholesome public opinion created about it if Christian couples give outstanding witness to faithfulness and harmony in their love, and to their concern for educating their children also, if they do their part in bringing about the needed cultural, psychological and social renewal on behalf of marriage and the family. Especially in the heart of their own families, young people should be aptly and seasonably instructed in the dignity, duty and work of married love. Trained thus in the cultivation of chastity, they will be able at a suitable age to enter a marriage of their own after an honorable courtship.