"Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4). Please rethink these questions as they are grievously erroneous. Marriage is a holy Sacrament, blessed and sanctified, whereby two become one before God, and with God; and vow to live their unified life. When a light is put out in a room, darkness settles and remains until the light break shines it, if possible once more. When God is not present in one's life, the devil fills that vacancy and freely dwells in that darkness. God will not be present nor be a companion in this relationship with when they are living together  purposefully without His blessing; as it is a sin.
When we do the “qal kidan” or marriage covenant. It is a sign of honoring God before living together in Holy matrimony. Not doing this is not inviting the blessing of God. It is not inviting God into your relationship. It is not helpful to either of you to be in darkness. Why not invite God’s light into your journey and honoring Him first before ever taking another step? This way, you are honoring Him and not allowing the devil space into your relationship.