Alex McLean's poem is about a relapse into low feelings. The speaker had believed the painful emotions and thoughts were behind them, but they have returned, and the word "again" appears over and over to show how tiring and discouraging that is. The poem doesn't say what caused the return, and it doesn't need to. What matters is the sinking sense of going backwards.
The speaker's feelings are weary, anxious and bitter. Seeing the world as "a blur of hatred" suggests everything has lost its clarity and warmth, and it's unclear whether that hatred is aimed at others, at the self, or at life in general. The closing image of a maze is the most telling: the speaker isn't wallowing, but trying to get out, and can't see the way. The mood is bleak and tense, but the short, plain lines also feel honest, like someone quietly admitting that things are hard again.