"For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh. So they are no longer two, but one. Therefore what God has joined together, let man not separate."
-Matthew 19:5-6, NIV
Holy Scripture affirms that man and woman were created for one another: "It is not good that the man should be alone."The woman, "flesh of his flesh," his equal, his nearest in all things, is given to him by God as a "helpmate"; she thus represents God from whom comes our help.
-Catechism of the Catholic Church, 1605
The matrimonial commitment is to be treated as a sacred commitment that requires a substantive preparation for service of God and neighbor in carrying out an important part of the Church's saving mission. This requires the commitment and the ability to commit to a bond that is permanent, faithful, and open to children. The couple (not the couple's parents) are to contact the Parish office no less than six months before their desired date of marriage. No commitments are to be made by the couple for facilities (church or reception hall), bridesmaids, groomsmen, or any other arrangements, until they have discussed them with the Priest and received his approval. The couple must have been interviewed and given approval by the Priest to schedule the date of the proposed wedding and have it reserved on the church calendar with the Parish secretary. No date is considered reserved until it has been reserved on both the church calendar and the Priest's calendar and the deposit has been paid to the Parish secretary. Baptism certificates are required for both members of the couple. Completion of a Weekend Encounter or having a Sponsor Couple is required. All plans for the wedding are contingent on the couple's successful completion of all the required preparations. Be sure to read over this Exortation Before Marriage
Also, please read the Catholic Bishops of Pennsylvania article titled "LIVING TOGETHER"