In stanza 6, why does the poet desire death? What does he then realize will be the result if he were to die?

The speaker finds a peace about dying in the forest with the nightingale. He wonders if this would make him part of the bird's world, if at least for a moment while it sings him to the eternal sleep. I think that the speaker realizes that death would not bring him into the nightingale's world. The nightingale is immortal, its songs heard through the generations. The man would simply die in the forest, still separate from the dream he so longs to be a part of.