The speaker is hurting over someone who keeps letting them down and never seems to see it. The word "again" opens each of the first three lines, so the poem feels like a loop: the same lies, the same broken hearts, the same walking past. Nothing changes, and that sameness is the pain. The repeated "never noticing" lands like a sore spot the speaker keeps pressing.
The short lines make the poem feel quiet and worn out rather than angry. The single word "cry" sits alone, as though the speaker is admitting how much this costs them, yet even that goes unseen. The ending is the sharpest moment. Putting "bye" in quotation marks suggests a goodbye that may be said, or only imagined, and the final question, "would you notice then?", sounds both hurt and a little testing. The mood is lonely and tired, with a faint hope that leaving might finally get the other person's attention.