The following passage is the introduction from the old rite of Marriage. I think that it sums up many of the things that we would want to bring to the mind of a couple who are being married.
N. and N., dosage you are about to be married. Now for children of God and members of the Catholic Church marriage is more than a human contract. It is something supernatural and holy and must be approached with that thought in mind. It was God himself who joined our first parents as husband and wife, and and with the first nuptial blessing made them the founders of the family and the home. And it was our divine Saviour who raised marriage to the dignity of a Sacrament, nurse thus adding to it the grace he won for us when he died upon the Cross. Remember what St Paul told the Ephesians. The union of a husband and wife is only to be compared with the union between Christ and his Church.
The life, therefore, to which God has called you, is noble and sublime. Yours it is to cooperate with God in his creation, bringing into the world new lives, to be children of the Church and heirs of the kingdom of heaven. Here today, before the altar, in the presence not only of your relatives and friends but of the angels of God and the whole court of heaven, your two lives are to be united in a bond that will endure as long as life shall last. May God in his goodness never cease to strengthen the love that unites you.
Have no fears but rather great confidence. Fulfil your religious duties, your prayer, your reception of the Sacraments. Learn to love each other, but also to understand each other, sometimes to put up with each other. Keep a place for Our Lord in your home. Where he is, there is no room for the evil things that can destroy your happiness and drive God’s grace away. Ask his holy Mother and St Joseph that they may be with you as well. Model your lives and your home upon theirs; and may their prayers obtain for you many years of happy life together.