Dominic Black's poem is a short, halting letter to someone who has died or is otherwise gone for good. The speaker opens by admitting how long it has been since they wrote, and the awkward question "Has it not?" makes the voice feel hesitant, as if they are still working up the nerve to begin. Almost at once they ask whether they even have the right to speak.
What drives the poem is guilt. The speaker feels regret and sorrow, and time has gone flat: every day is "just another now" and "just another tomorrow," with no sense of moving forward. The simple rhymes and short lines add to this stuck, circling feeling.
The ending is the most painful part. The speaker wants to apologize but cannot, because the other person is "no longer here" and no goodbye was ever said. The mood is heavy and raw, full of the helplessness of having something important left unsaid.