FAQ for
Stranger Than Fiction (2006) More at IMDbPro »

In the book, Harold (the character) does not know that he will die saving the child; he steps in front of the bus without thinking, saves the boy, and is killed. In real life, Harold knows that if he saves the child, he will die. Even though he knows it means his death, the real Harold steps in front of the bus and saves the little boy. In Karen Eiffel's eyes, the actions of the real Harold are so noble and courageous that it warrants keeping him alive: The character Harold unknowingly steps into his death, while the real Harold was willing to give his life for someone else. (What makes this special is that Eiffel is able to swallow her pride at the chance of a perfect ending in order to save Harold.)

Harold loved Ana and did not want to burden her with the knowledge that he was going to die. He had come to fully appreciate life and wanted to enjoy his last moments. If he had told Ana, she undoubtedly would have tried to talk him out of it, which would have made their last moments together unpleasant. Additionally, although he had come to accept his fate, Ana would not have understood his decision.

"(I'd Go The) Whole Wide World" by Wreckless Eric