Answer:
I am a way to say goodbye to your sweetheart
When I am caught I am thrown away. When I escape you itch all day.
I am a person who pretends to be someone else
A butcher is 6 feet tall and wears size 12 shoes. What does he weigh?
Never ahead, ever behind, yet flying swiftly past, for a child, I last forever, for adults, I'm gone too fast.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.