MATRIMONY
Marriage is a Covenant, a union that bonds a man and woman together during their life together.
The sacrament of Matrimony signifies the union of Christ and the Church. It gives spouses the grace to love each other with the love with which Christ has loved his Church; the grace of the sacrament thus perfects the human love of the spouses, strengthens their indissoluble unity, and sanctifies them on the way to eternal life. (CCC 1661)
The love in a married relationship is exemplified in the total gift of one’s self to another. It’s this self-giving and self-sacrificing love that we see in our other model of marriage, the relationship between Christ and the Church.
Marriage is based on the consent of the contracting parties, that is, on their will to give themselves, each to the other, mutually and definitively, in order to live a covenant of faithful and fruitful love. (CCC 1662) The Church takes the lifelong nature of the Sacrament of Marriage seriously.
The Church teaches that a break in this covenant goes against the natural law of God:
The remarriage of persons divorced from a living, lawful spouse contravenes the plan and law of God as taught by Christ. They are not separated from the Church, but they cannot receive Eucharistic communion. They will lead Christian lives especially by educating their children in the faith. (CCC 1665)