Catholic preparation for marriage includes the following:
The Sacrament of Marriage is a visible sign of God’s love for the Church. When a man and a woman are married in the Church, they receive the grace needed for a lifelong bond of unity.
The Sacrament of Marriage is a covenantal union in the image of the covenants between God and his people with Abraham and later with Moses at Mt. Sinai. This divine covenant can never be broken. Marriage is a union that bonds spouses together during their entire lifetime.
The love in a married relationship is shown through the free and total gift of one’s self to another and for another. In this way, marriage reflects the the self-giving and self-sacrificial relationship between Christ and the Church.
"The Sacrament of [Marriage] 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" (Catechism of the Catholic Church, 1661).
Marriage also reflects the Holy Trinity. We believe that God exists in eternal communion. The Father, Son, and Holy Spirit are united in one being with no beginning and no end. Human beings, likewise, were created by God in God’s image for the purpose of communion with another human being.
The Christian family is a communion of persons, a sign and image of the communion of the Father and the Son in the Holy Spirit. In the same way that the Holy Spirit is the fruit of the love between the Father and the Son, a child is the fruit of the love between a husband and a wife. Christian marriage at its finest is a reflection of God’s self-giving love expressed between the love of two people.