There was another thing that i think is related to the narrator's feeling.
This poem mentioned a lot about the leaves and flowers are gone and one line that said "over the crust snow" (11). Both of them shows the season of this poem which is the end of fall and the beginning of the winter.
Winter always means to something that is old or things almost dead. If we see the last two lines "and bow accept the end/of a love or a season" which also means end, we can see something (maybe heart) of narrator is dead or nearly dead. This shows the tone of this poem is negative.