Before the poem proper begins, its title has already thrown something out of a window. "I Threw the Supermarket Flowers From the Windowsill" is a complete sentence in the past tense, a finished act, while everything that follows is in the present and never mentions flowers again. That gap is where much of the poem's meaning sits. Supermarket flowers are the cheap, last-minute kind, a gesture of care or apology that is easy to buy and easy to mean too little. The poem doesn't say who bought them or why they were thrown away, but the act reads as a refusal of comfort, or of a peace offering that arrived too late or too cheaply.
The central idea is a pain that has outlasted every attempt to be rid of it, and a distance that neither person can cross. The opening line, "The pain you made me feel", speaks straight to an unnamed "you", and the speaker never softens the accusation. What follows is blunt: "It's unbareable / I hate it". Then comes the poem's most honest turn: "But it has never gone away". The word "But" shows that hating the pain has not weakened it. Anger, the poem suggests, is not a cure.
The image that holds the poem together is the glass wall. It echoes the windowsill of the title, so the window the flowers were thrown from becomes the barrier between the two people. Glass is a clever choice because it separates without hiding. The "you" is "Waiting / Watching me cry myself to sleep", so they can see everything and touch nothing. The speaker "knows" they are there, a verb that suggests a felt presence rather than something seen, and the poem never says whether the watcher is physically on the other side or only in the speaker's mind. The wall could be distance, estrangement or something more final. The text leaves that open, and the openness lets many readers recognise their own situation.
The form does a lot with very little. There is no regular rhyme and no steady rhythm, only short, plain lines that sound like speech. "Waiting" stands alone on its own line, so the reader has to wait too, and the pause makes the stillness of the watcher almost physical. Then the poem stretches into its longest line, "And you can't do anything about it because your on the opposite side of this glass wall", which seems to run on like the distance it describes. After that comes the short, flat ending: "We are separated and that's that". The repeated "that's that" sounds like someone closing a door, but the poem has no full stops at all, and the claim of finality sits uneasily against that. A speaker who has to announce that it is over, and whose pain "has never gone away", may not believe it is.
The poem also has some spelling and grammar slips, "unbareable" and "your" for "you're", twice. Judging by the effect, they give the piece the feel of something written quickly and left unpolished, closer to a raw message than a crafted statement. Whether intended or not, "unbareable" brings "bare" to mind, and the poem is stripped of ornament in just that way. It has no elaborate metaphors beyond the one wall, and no consoling turn at the end.
One more tension runs through the poem. The "you" caused the pain, yet the speaker pictures them as helpless, unable to "do anything about it". That is a small gesture of sympathy inside the accusation. The speaker does not describe a villain, only someone who is close enough to watch the damage and too far away to repair it. That is a more uncomfortable and more believable picture than simple blame.
What makes the poem worth reading is this honesty about stalemate. It does not heal, forgive or find a lesson, and it offers no neat resolution. Instead it holds one image, a transparent barrier, and lets it carry the whole emotional weight. For students, it shows how a poem can be effective without technical display: a title that implies a story, a single well-chosen image, and an ending that tries to sound final and doesn't quite manage it.