Marriage without a License?

Today, many men and women are living together without being married. But is such an arrangement acceptable in God’s eyes? Or is this conduct equated in Scripture with fornication? How does a marriage begin? Did God create Adam and Eve as husband and wife? Is marriage a covenant which is preceded by engagement or betrothal? What about a wedding and a wedding supper? How about adultery and divorce? What connection is there between a physical marriage and the spiritual marriage between the Church of God as the bride and Jesus Christ as the bridegroom?