I disagree with your implications that it’s OK to live together as long as God knows your heart. What kind of picture are you painting for other people? That anything goes? Forgive me if I have interrupted this wrong, but I think you need to take another look at what you are teaching people.
According to my research, marriage licenses originated in England in the 1500s. They were originally intended as a shortcut that simplified the marriage formality but also became a revenue source for the church. Prior to that all marriages were what we would call common law marriages. This type of marriage is still routine in many parts of the world and requires only that the two people must agree that they are married, live together, and present themselves before God and the community as husband and wife, just like people did for the first 4500 years of human existence. These days the marriage license is also used as a legal document for community property and estate purposes.
So the marriage license is a document devised by man, not God. The existence of one doesn’t necessarily constitute a marriage in His sight, and neither does the absence of one disqualify it. It’s what’s in our heart that counts with Him.