While I suppose we should not be surprised by the evil that takes place in this world, sexual sins always seem to be worse. They are not only a violation of one's body, they are usually also a violation of one's trust. They are of such a personal and intimate nature that even criminals find them appalling. (As I understand it, criminals carry out their own brand of justice on such offenders once they are put in jail.)
I wonder why such sins are, sadly, so common. I have some guesses. I can think of numerous factors which attribute to people's utter lack of self-control and/or sense of entitlement. These factors include pornography which, thanks to the internet, can be brought into the home of anyone. In fact, there barely seems to be any stigma associated with pornography any longer. People boast openly about their desires to watch it. It is normalized, and that emboldens others to view it. If people feed their brains with these graphic images, what makes us surprised that they want to act out on them in real life? The virtual image only stokes up desires; and those desires crave to be gratified in reality.
While not actually porn, much of what we choose to entertain ourselves with on TV, at the movies, and even in our music encourages and glorifies sex. (It is usually called "love" in many songs; but who is kidding whom?) It encourages people to act out, to gratify lusts, and once again to normalize using other people for one's own pleasure and gain. Perversion is celebrated. Promiscuity is cheered. Am I overstating it? Listen to a rock star boast of his sexual exploits to a concert hall full of people, and then listen to the fans roar with approval. No one wretches in disgust.
Meanwhile, the Christian Church continues to proclaim the 6th Commandment, to encourage self-control of one's urges, to promote the sanctity of marriage, and to declare that God's intent for sexual happiness is limited to a husband and wife. Hebrews 13:4 is pretty pointed on that: "Marriage should be honored by all and the marriage bed kept pure; for God will judge the adulterer and all the sexually immoral." Christians do not call sex dirty. We agree with God--sex within marriage is pure. It is blessed. It is God's design that sex be restricted to the marriage bed so that, should pregnancy result, a father and mother who are united in marriage are united all the more to parent the child with whom God has blessed them.
Unfortunately, the world condemns the Church's teaching of God's design as prudish and oppressive. Of course, if God's design is followed, rampant sexual misconduct would be reduced dramatically. Men would understand that any woman to whom he has not committed himself as her husband means that he keeps his hands off. He even puts to death the thoughts about her that are impure. She is not his; and therefore he respectfully treats her as belonging to another--whether she is married to another man or may potentially be married to another man someday. (I am not naive enough to believe that the evils would stop. There will always be the adulterers and the sexually immoral, and that will always be sad and evil.)
While encouraging people to behave is a noble goal, the Church also desires to call to repentance those who have fallen into sexual sins so that they will not be consumed by them and condemned for them. We proclaim Christ--whose love is seen not in seeking what he can get out of people, but by laying down his life for the salvation of all. As a faithful groom, Jesus has done all things for the good of his bride, the Church. He removes every shameful stain from her, covers her blemishes, and makes her beautiful and radiant. He remains forever devoted to her and faithfully seeks to glorify her. That is what love is supposed to look like; and in Christ, it does.
For your edification and amusement, check out this video from Lutheran Satire which is related to this topic.