Calling all apologists!

You know I'm rereading The Da Vinci Hoax. The first time through, I did start to wonder why Jesus couldn't have been married. Mind you, I never went to the fantasy realm of "He was but it was hidden," but the question of "Why not?" was bouncing around in my head.
I dawned on me one evening as I was brushing my teeth. Duh, His bride is the Church. Hit me upside the head with a grouper, why don't you? And yeah, it's sinking in now this second time through.
Anyway, I was discussing this with a non-Christian friend (who probably will read this, so if you comment, be charitable). She finds Jesus' lack of sex unnatural. She doesn't question his celibacy, as far as I know, just the naturalness of it. If He were here on earth to have the full human experience, sex would have to be included.
That assumes the goal of the Incarnation was to have the human experience, not to redeem us from sin, which as a Christian is what I believe. The means was taking on flesh, not the end. His goal was to save us through being human.
She also questions Mary's perpetual virginity. Her opinion is that Jesus would not have been born into an unnatural relationship, which is what Joseph and Mary would have had (given that it was not sexual in nature).
I explained the idea of the Jewish tabernacle, where God dwelt, and its inviolability. Being a good and observant Jew, Joseph wouldn't have to be told that bit twice. There's also that ancient Jewish tradition of a husband ceasing relations with a wife after rape or adultery (at least, if he were a priest). Though Mary was neither raped nor adulterous, and Joseph a carpenter not a priest, she did bear a child not her husband's, so it would make sense that he would not have relations with her.

My question to all of you apologists is, how to explain this stuff to a non-Christian? Sex is a natural thing. True. It's a very good thing. It's God's invitation to create the best He's done with Him: another human being. I know it's not a right, it's a gift or privilege.
So how to explain that it's not unnatural not to have it?