As I said, it was up to Jack to stop the madness. Tyler gets to him before he can disable the bombs that are going to blow up the credit card buildings and beats him up. Next thing you know, Jack is tied up in a chair with the gun in his mouth held by none other than Tyler Durden. This is where the movie began. By now, Jack knows the reason Tyler left. Tyler had told Jack never to talk to Marla about him, to never say anything about knowing Tyler Durden, but, Jack did. The reason why Tyler never wanted Jack to say anything about him was because Tyler is Jack. Tyler is Jack's alter ego, imaginary friend, whatever you want to call it. He even explains in the movie, "All the ways you wish to be, that's me." So, now Marla knows too much. Marla is brought up to the building that Jack and Tyler are in. But, before she gets there Jack shoots himself in order to kill Tyler. Luckily, Jack lives through it and Tyler dies (how Jack lives on while Tyler dies-don't ask me how-I don't know). Then, Marla gets there. Jack and Marla hold hands while watching all the other buildings blow up. He didn't save the day, so what?
