Recently finishing up the book Fight Club after being a fan of the movie for so long. While the movie retains most of the dialogue and several tones of the book, one giant contrast is now present to me.
In the book, the ending goes similar to how the movie occurs. However, one glaring difference is while in the movie, the Narrator shoots himself through the cheek, doing this kills Tyler, and he and Marla stand atop the building, watching the destruction caused by Project Mayhem in a seemingly (while twisted) peaceful ending.
In the book, however,
The Narrator shoots himself, but is then put into a mental health facility until the end of his days. To me, this seems like a heavy contrast and much more depressing ending to the story compared with the movie version. Also in the book, there is more hostility towards the Narrator when he tries to stop Project Mayhem while near the end of the movie, they seem to "forgive" him by bringing Marla to him.
Is there any reason to these changes or documentation stating why Fincher decided to take these turns with the story?