The Patriarch Abraham and his wife Sarah represent the fullness of marriage.  Throughout their long lives, their love for each other continues to burn brightly, and in their son Isaac, God blesses their love.  The Prophets of the Old Testament saw this intimate union of a man and woman as the image of the union between God and his people, the Daughter Zion.  John the Baptist knew The Lord Jesus as the Bridegroom of the Church.  The Lord spoke of himself in those terms.  In his little book, "On the Four-fold Marriage", Pope Innocent III (d. 1216) wrote of the sanctity of marriage:

"The Sacred Scriptures teach us that there are four types of marriage according to the four modes of theological understanding: the historical, the allegorical, the moral, and the anagogic.  The first occurs between a man and a woman according to the law; the second is between Christ and his Holy Church; the third is between God and the just soul; and the fourth is between the Word and human nature.  Concerning the first type of marriage, the first man prophesied, upon his waking: 'For this reason a man shall leave his father and mother, and cling to his wife, and the two shall be in one flesh' (Genesis 2, 24).  Concerning the second type of marriage, the angel says to John, in the Book of Revelation: 'Come, and I will show you the Bride, the spouse of the Lamb' (Revelation 21, 9).  Concerning the third type of marriage, The Lord says through the Prophet Hosea: 'I will espouse you to myself in justice, in judgment, in mercy, and with mercy' (Hosea 2, 19).  Concerning the fourth type of marriage, the Bride says, in the Song of Songs: Go forth, daughter of Zion, and see King Solomon with the diamond crown with which his mother crowned him on the day of his betrothal' (Song of Songs 3, 11).  As though to say, Daughter of Zion -- the weak Jews, or carnal men -- Go forth -- from the darkness of unfaithfulness and ignorance -- And see -- with the eyes of the heart, not the eyes of the flesh -- And see -- believe in -- King Solomon -- Christ, the true peacemaker -- who makes both peoples one (cf. Ephesians 2, 14) -- With the diamond crown with which his mother crowned him -- in the singular grace by which the Virgin Mary conceived him without the urging of the flesh, the heat of carnal desire, the taint of sin, but instead holy, pure, and without stain."