They are flesh and blood, and keep demonstrating their ignorance of sex. They have this idea that sex has to be "justified" by being specifically for procreation. That is the misconception that guides Humanae Vitae, which asserts it is "natural law". All too often "natural law" is used in theological argument to mean "in my opinion" or, worse, "I don't have an actual argument, so I'm just going to say 'natural law' and hope no one notices I'm just hand-waving". 

I understand the meaning of sin. I do not believe that God is as concerned about sex as the hierarchs do. Their refusal to accept gays is far more sinful, IMHO.

I say that the magisterium is wrong. , I know you have this idea that differing from the magisterium by one iota means one has left the Catholic Church. You have said, in as many words, that your beliefs are completely congruent with the magisterium, and thus to disagree with YOU places one outside the Church. You substitute your opinions for the will of God.