Living together in advance will diminish rather than improve your chances of success. CCNA is not interested in what the world thinks or believes. We are only interested in what the heavenly Father thinks. God created the institutions of marriage and the family. I am not interested in opinions, only in what the Word of God says.
Marriage is a divine ordinance.
The Bible does not teach cohabitation. God calls cohabitation adultery or fornication. If a couple is living outside a legal and sanctified relationship, their faith will not work, their prayer life will never work, and there will never be a real harmony in that relationship. Without marriage as a divine ordinance, you will not have a family. You may have a group of people all living in the same house, but you will not have a family.