Catechism of the Catholic Church §1614 — excerpt
In his preaching Jesus unequivocally taught the original meaning of the union of man and woman as the Creator willed it from the beginning permission given by Moses to divorce one's wife was a concession to the hardness of hearts.
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.