That piece of bark is just a symbol.
Something I thought would last is broken.
It can never be fixed.
But the tree remains, physically and as a memory.
You keep that memory.
You keep that piece of bark.
One day, the bark can return to the tree.
Either with or without me.
I wonder if I should think of this in a literal or figurative sense. Either way, the nostalgic feel is always a nice touch...Maybe you had planted this tree with the person you loved? Or carved each other's initials into it...? Or simply laid underneathe in it's shade :3 Either way, I think this is a lovely poem, a bit sad, and personal - but those are the best kind. ;)