Catechism of the Catholic Church §1638 — excerpt
"From a valid marriage arises a bond between the spouses which by its very nature is perpetual and exclusive; furthermore, in a Christian marriage the spouses are strengthened and, as it were, consecrated for the duties and the dignity of their state by a special sacrament."
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: CIC, can. 1134