Precious, Lunasea

I realised after parting you
That I can't sing well

The voice that's haunted my brain
The words of promise we made
To make a new start

Strange pride blind-folds me
And I can't sing well

Even if I go back to the beginning of this puzzle
And start solving all over again
I can't remember that crucial word..

If I force myself to cease to exist
I'll probably feel much better

The voice that's haunted my brain
The word of an outsider that marks the end

If I wake up from my dream now
And everything was back to normal..
I'm still searching for the key I'll never find,
lost deep in my memory

I can't go back to then
I can't even undo my errors
I can't return to then
I can't even undo my sins

..
I want to deliver that word