"A slumber did my spirit seal," says the poet. That is, a deep sleep 'closed off' his soul (or mind). How does the poet react to his loved one's death? Does he feel bitter grief? Or does he feel a great peace?
Though his loved one's death has left the poet numb and the "common human fears" no longer affected him, his reaction cannot be labelled as "bitter grief". This is because by the end of the poem, we come to know that the poet imagines her to be a part of nature, rotating with the earth on its axis. He takes consolation from the fact that she is still alive in the nature and is beyond life's trials. This promotes the idea that he feels a "great peace" of mind. Thus, we can conclude that the poet's feelings are ambiguous.