Nothing in "Stay" says that anyone has died or gone away, and that is what makes it unusual. The people the speaker misses are alive and changing: the line about "those who they become" shows that. The loss here is the quiet kind that time causes, when someone turns into a new version of themselves and the earlier one disappears. The central idea is that joy and mourning can attach to the same person at once. The speaker is proud of who they are now and grieves for who they were, and the poem refuses to say which feeling wins.
The structure rests on pronouns, which move in a clear sequence: "her," "them," "me," "us," "you." The poem opens with "I miss her," then widens at once to "I miss them all," so one particular person seems to open out into a crowd. After the long central lines, the opening is mirrored almost exactly: "I miss me. I miss us all." The speaker is among the missing. Even the sound of "her" and "me" echoes between the two versions. Both patterns end on "all," and the word comes back in "I will fight for you all." Because the poem has no rhyme scheme and no regular meter, this repeated word works as its refrain. Each sentence is short, flat and nearly bare, as if the speaker has no energy left for decoration.
The two longest lines carry the poem's real argument: "My happiness for seeing those who they become / Is challenged by my sorrow for the loss of those who they were." The sentence is balanced like a scale, with happiness against sorrow, "become" against "were," and seeing against loss. The blank line falls just before the verb "Is," so the reader has to cross a gap to finish the thought. That gap seems to act out the distance between past and present. The choice of "challenged" matters too. Happiness is not destroyed or cancelled, only contested, and the word of combat quietly prepares for the "fight" that follows. The phrasing "those who they become" is a little awkward, the way speech is when someone is trying hard to be exact about a feeling.
The last stanza is where the poem turns to "you," addressing the missed people directly for the first time. Here we get the poem's only real image: "the light that you created." Until now the language has been abstract, all missing and happiness and sorrow, and this one picture is the more striking for it. Light is something other people have made inside the speaker, so the speaker is a kind of lantern lit by others. The vow is measured against that gift: "I will fight for you all / Until there remains in me none of the light." The fight ends only when the light is spent. The inverted phrasing, "there remains in me none," sounds like an oath, and "fight" and "light" make the poem's only true rhyme. It falls inside the lines rather than at their ends, so it is easy to feel without quite noticing.
Then the grand tone drops away. "Stay with me please" is the shortest line, and the word "please" comes last, like an afterthought or a crack in the voice. After a vow of endless fighting, the speaker admits that fighting is not what they need. They need company. The poem never says who is being asked to stay: the people themselves, the earlier versions of them, or the "us" that has been lost. That openness lets readers fill the line with their own people. There is also a tension in it. The speaker has just said they are happy to see who these people are becoming, yet asks them to stay, a request that change makes impossible to grant fully.
What makes the poem worth reading is its honesty about a feeling that rarely gets a name: mourning people who are still here, and mourning ourselves too. It does this with very little, using plain words, one repeated structure, one image of light and one small, desperate request. For a student, it shows how a poem can be powerful without rhyme or ornament, when the shape of its sentences and the order of its pronouns carry the emotion.