Question about sexual morality

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.

I don’t believe in " sinning against oneself" or others. We sin against God. That is not to say that any personal evil does not have social consequences. After all, we live in the consequences of the Fall. I also believe that sexual sins may, in fact, be one of the most forgiven by a loving Father, given our natural propensities in our Fallen nature. This does not excuse our failures, but may mitigate our punishment in the eyes of our Father, who sees through us like a window. We should be afraid of falling into a continuous situation of sin, as many relationships set up social consequences that are a continuing failure before the Lord and he will not be trifled with. We sometimes find that the social requirements of our sin leads us to being failures for those we are dealing with in these sins. That is the social impact of evil. It is so easy to be seduced into thinking our sexual immoralities are a consequence of love for another. If it is wrong for God it is against the natural good that will fulfil our own natures. Aberrant actions with another is not naturally founded in love, no matter what mental gymnastics we perform. However falling into the mercy of Our Lord works for me no matter how I despise my own continuous weakness.

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