In order to contract marriage validly, the spouses have to be of age to marry and consent freely to their vows.
Catholics must celebrate their marriage before their parish priest or the local Ordinary or a priest designated by one of them, in the presence of at least two witnesses.
The nuptial blessing, though not necessary for the sacrament, is given to sanctify the union of the spouses in the name of the Church and to call down God’s blessings upon them more abundantly.
If one of the spouses is not Catholic, the Church can sometimes allow this sort of union with a dispensation for differing cults or mixed religions. As the guardian of souls, the Church requires a very serious reason, and requires of the non-Catholic spouse a promise to spare the Catholic spouse any danger of perversion or neglect of the Faith. She requires that all the children be baptized and raised in the Catholic Church.
The principal obligations of persons united by marriage are inviolable conjugal fidelity and a Christian behavior in all things; to love each other and bear with each other and live in peace and harmony; and to provide for the needs of their children by giving them a Catholic education and leaving them free to choose the state to which they are called by God.