Catechism of the Catholic Church §1642 — excerpt
Christ is the source of this grace. "Just as of old God encountered his people with a covenant of love and fidelity, so our Savior, the spouse of the Church, now encounters Christian spouses through the sacrament of Matrimony."
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: GS 48 # 2 · Tertullian, Ad uxorem. 2, 8, 6-7: PL 1, 1412-1413 · FC 13