In the Pauline epistles (I believe it was Romans IIRC), Paul tells us that all other sins a man commits against others, but sexual morality is a sin he commits against himself.
Now as I understand it, one of the major talking points about the consequences of sexual immorality is how it erodes families, which are the building blocks of a healthy society. C.S. Lewis once described it as distinguishing between two kinds of evil. The first kind of evil are those that have immediate consequences. So if you were to compare it to a fleet of ships, if one of the helmsmen of the ship were to steer his ship 10 degree to the left, he would crash into another ship. The 2nd kind of sins were those that were internal sins. So if the captain of a ship never maintains his ship or checks the integrity of the hull, of the equipment, etc., than the ship will inevitability sink or crash into another ship.
How should I be understanding St. Paul’s statement on sexual morality? Is it a sin against oneself in the sense that in a voluntary sexual exchange (such as between fornicating lovers or between a prostitute and client) you are not maliciously causing the other person harm, but as a result of the action, both parties in the encounter are sinning against themselves?
edit: Okay, I may have answered my own question after I wrote it down and then edited it to expand my response. Please feel free to comment.