Final answer:
The speaker reacts poorly to the raven's 'nevermore' because it represents an inescapable reality of despair and the finality of loss, which torments him and portrays the raven as a prophet of doom.
Step-by-step explanation:
The speaker reacts poorly to the raven's response of "nevermore" in stanzas 15-16 because the raven's repeated utterance serves as a dark omen, symbolically representing a finality and hopelessness that resonates with the speaker's own sorrow. The raven, a mysterious and ominous bird, speaks only one word, "nevermore," which the speaker initially finds curiously apt and even amusing, but soon the repetition of this grim word begins to torment him. As the speaker seeks answers to his deep existential questions, the raven's unchanging response suggests that there is no escape from his despair. This leads to a growing frustration and terror as the speaker realizes that the bird's simple refrain may hold a deeper, more tragic truth about his own fate and the impossibility of reuniting with his lost love, Lenore.
The bleak and unyielding nature of the raven's message—"nevermore"—is what ultimately leads the speaker to react negatively, seeing the raven as a prophet of doom rather than a source of solace or guidance. This change in sentiment is depicted in the closing stanzas, where the speaker implores the raven to leave and begins to view its presence as a form of torture, a symbol of his unending sorrow and the cruel, unrelenting nature of fate.