Four short lines trace the sudden collapse of a good moment. The speaker remembers a happy day spent talking, though the conversation had "no sense," which suggests it was easy and light, the kind of chatter people enjoy without needing it to mean anything. Then night arrives, cold, and the mood flips. The speaker's throat fills with dust, an image of dryness and silence, as if the words that came so freely earlier have now turned to something choking.
What hurts most is the speaker's own self-blame. They feel "heartsick" for being "too dense," as though they missed signs that something was wrong. The final line is a question asked in confusion: why, and what has become of us? The phrase "us" hints at a relationship that has changed or ended, though the poem doesn't say how. That vagueness is part of its effect. The mood is quiet, bewildered, and sad, and the speaker is left with questions and no answers.