I find that a peculiar analysis, imposed on nature, not found there. The important moral values in sex are honesty, mutual consideration and responsibility, not chastity as such or marriage as such. (Chastity is a recognized form of self-denial, but self-denial is simply one of the legitimate options.)Sin is simply a distortion of the natural and or divine order. Sexual desire is a part of the natural order (even human beings without concupiscence would experience it) but not beyond its natural ordering which is in marriage and procreation.
Tell me about it!To understand this think of how often it is that people do very stupid things when they listen to their genitals over their heads.
Nonetheless that contradicts your claim for Jesus, who, you said, was not subject to passion. Amending this to make him subject only to 'proper' passion makes him indistinguishable from the great majority of the human race.Passion when ordered properly is a good thing. The desire to get married and experience sexual intimacy is a good and natural thing. Feeling anger in the face of legitimate outrage is a good thing.