If you allow yourself to become fixated on that illusion, you lose vital objectivity. You must be able to interact with that illusion. Bite your authorial tongue if they don't tell the unvarnished truth. When you let go, you allow your cast's individual narrative voices begin to shine through. Your narrative has a life of its own.
Story gives rise to story.
Like the empty-handed fisherman, your characters have ego and motivation to tell the story as THEY see fit. The present as the characters reveal it. The future the writer has plotted out. The future as a function of how the characters respond to the present. The future as reconstructed by characters' reactions.