1 Corinthians 6:18

Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body (KJV)

Then: Since Paul tells the Corinthians to get away from sexual immoralities as fast as possible, you'd think that would be his final word. It's not. Their reasonings needed an overhaul so that the most important element would govern their convictions. Baker reviews the Greek attitude of dividing a human's life so that the spiritual was always pure while sinful actions involved the physical being (Baker, p. 94). The Corinthians latched onto that explanation. It let them sin sexually and supposedly maintain purity before God. Paul says unh, unh! All other sins bring hurt and pain to fellow human beings and can be easily ignored. Sexual sins afflict the partner, the sinner himself and the participating body of Christ.

Now: In terms that we don't ordinarily consider, Paul's reasoning still holds true. We think about the abusive use of alcohol, drugs, food, or some who cut their own bodies. Don't those actions afflict harm on the person himself? Since they do, we know Paul directs his concern to what he's already said about "His own body" being joined, united, with Christ. Even though, sexual immorality causes personal emotional and psychological pain, its most egregious harm is its betrayal of the body of Christ. Paul doesn't delineate the aggressive versus the passive partner here. His advice is for both. Flee. That has to happen before restoration and reconciliation with Christ - issues which Paul discusses elsewhere, not here.

Extra source: Cornerstone Biblical Commentary 1 Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.