The speaker looks at the emotions other people seem to share and finds nothing there to connect with. Every line is a plain statement of distance: "I don't feel," "I don't comprehend," "I don't see the point." The title, "nothing," fits that blankness. The speaker isn't angry or dramatic, just puzzled and a little detached.
The one question in the poem, "Why does this make you feel this way?", is addressed to someone else, and it sounds less like curiosity than like a gap that can't be crossed. Near the end, the speaker wonders, "Maybe I'm the anomaly," which hints at some self-doubt or loneliness. But the last line, "I will never understand," shuts the door firmly. The short, flat sentences and the repeated "I don't" create a cold, numb, slightly isolated mood. Judging by the wording, the speaker may be resigned to being different rather than trying to change.