The 2nd table. As our love of God is reflected in our love for the neighbor. We dealt with respecting his person and now we deal with the neighbors marriage and our respect for his marriage state. Today marriage is maligned and sexuality is as bestiality today. The idea of marriage and sexuality is under attack and we need to be equipped with the Word of God, being devoted to the cause of the Kingdom.
To set this command straight is to defend marriage. Adultery speaks to marriage and fornication primarily speaks to that outside of marriage. The point is the/our relationship to marriage.
When you take something beautiful out of its context and use if for our own purposes, something beautiful becomes very ugly. And we see that in the world around us today. Look at their concerns. It has become animalistic! Marriage was given for the good order of society and for the cause of His Kingdom and covenant, and was God's purpose to give us sexuality to use for good. So important is the marriage state that He has made it a picture of Christ and His Church. The bride and the bridegroom! And all the spiritual intimacies between Christ and His Church are reflected in the marriage bond! God gives sexuality and limits it to the marriage! Our liberty is in Christ and God states in the commandments "Thou shalt not commit adultery." Furthermore, we are temples of the Holy Spirit and when you violate the 7th commandment you sin against your OWN body. Flee fornication as Joseph did. The standard of a sanctified life and the way we live have NEVER changed. God set them in place and they are still the same today! He also forbids those things that would lead us to a violation of the commandment. This includes words, gestures, behavior, actions, etc. A commandment that we all struggle with in our flesh.
There is a purpose for all of this. It is within our relationship with God that we date, court, marry, respect, and live properly in and with our relationships to one another. God also conceives HIS Church in the intimacies of marriage. You may be courting someone else's wife as someone may be courting YOUR wife.
Respect that God has limited these things to the marriage bond that we may be sanctified to His Glory!