This is the tricky part. Their “contract” was written for them by a religion claiming to have divine knowledge. If that claim was false, then what status does the contract have? A marriage contract in the Bible (OT) is between groom and bride’s father btw. There is no religious support for husband-wife vows or for prohibiting polygamy. These may be good- but don’t mix God in! But what would marriages look like if the divine wasn’t used to shame.