Your stock response to melancholy will blind you to anything that challenges that response. As a result, you will seriously misread the poem. Distinguish between fundamentals and overtones. Poets love to play with the nuances in words, with connotations, with layered meaning. To help insure that the message is correctly received.
Repetition is a subtle meta-discourse guide to understanding.
If you are having problems with a section of the text, consider the possibility that the poet is using a metaphor. Pay attention to significant contrasts . Structuralists would use the term binary oppositions. Like New Critics , structuralists emphasize the importance of contrasts in generating thematic meaning in the text. Darth Vader vs Luke Skywalker, Keats' Grecian urn as a symbol for the eternal nature art vs life as a timebound process, etc.