Right from the Compendium of the Catechism of the Catholic Church. I don't think it can be any clearer what the church teaches about marriage and divorce:
347. What sins are gravely opposed to the sacrament of Matrimony?
Adultery and polygamy are opposed to the sacrament of matrimony because they contradict the equal dignity of man and woman and the unity and exclusivity of married love. Other sins include the deliberate refusal of one’s procreative potential which deprives conjugal love of the gift of children and divorce which goes against the indissolubility of marriage.
Here is a link to the compendium: