Despair fuels Frodo’s indecision. The Black Gate is under heavy surveillance, and it’s growing more dangerous for the hobbits to linger. This fact, combined with the moment of levity provided by Sam, breaks Frodo from his doubt and enables him to make his choice. Ultimately, he can wish things were different—that he didn’t have to bear his burden or that Gandalf were there to help him—but the facts remain that he agreed to take on the quest and must see it through with whatever skills he possesses. To keep moving, he has to make a choice, even if it turns out to be the wrong one.