Answer:
A young man wants to have me but when he has me he no longer wants me. Blade in hand he attacks me and does his best to remove me. Yet he knows that it is all in vain.
You find me behind the stars; or in a sixth seventh or third. It takes something round a computer and me to make pie. I am bigger than anything you can think of.
I begin your sentences.
I am so delicate that even mentioning me breaks me. What am I?
Deep, deep, do they go. Spreading out as they go. Never needing any air. They are sometimes as fine as hair.
A little house full of meat, no door to go in and eat.