This poem is a monologue from the author's heart. You can be ignored in it. Obviously, the author doesn't care much about others. He is always self-centered. The full text shows his maverick, pretending to be cold. The dead corner is the black box, where the author collects small secrets; Secrets, easy to understand, are things you don't want others to know; Blood is a metaphor for pouring emotions. The author is only willing to pour his feelings on the wound and doesn't care about the concern of others. The meaning of heat, sadness and grievance is similar to that of blood. It is in these respects that the author is very narcissistic.
"I love you most when I can't see you/feel lonely" means that the author never intends to tell others his inner feelings, or that he thinks others can't understand his feelings. His self-righteous love/loneliness is only his inner self-appreciation.
The last two paragraphs can be regarded as the author's direct confession. It is his real idea to get rid of May, not that others are selfish, but that the author is very self-righteous. In fact, the "you" in the text is a big head, and people who don't understand will think that she is selfish and heartless. In fact, this "you" is invented by the author to cover up his true thoughts, that is, narcissism, ignorance and self-righteousness.
Okay, is there anything you don't understand? I wonder, does this help you?