There appears to be no victim. Fornication and prostitution are morally wrong, but they are not wrong by dint of applying the Golden Rule. There is, too, a limited sense in which the moral value of sexual acts depends upon subjective satisfaction. Not finally or decisively, of course. But part of the appeal and the rightness of the marital act is precisely that it allows the couple to experience, or actualize, their marriage.
Sexual acts are, of course, pleasurable.
And that is just fine, and welcome, where the act is otherwise licit. Which is to say, where it is the marital act. The temptation to rationalize sexual misbehavior is very great, because the emotions are so powerfully engaged in the acts themselves. This is true especially where the meaning of marriage has been transformed. Then marriage cannot be understood to be essentially related to children and reproduction.