A speaker sits alone with thoughts of someone they miss and can't reach. The poem is built almost entirely out of one word, "wonder," which keeps coming back until it starts to feel like a loop the speaker can't get out of. They begin with a big question, what is this person doing right now, then slide into tiny, oddly specific ones: what color is their shirt, and how does it smell? Those small details make the longing feel real. It's the kind of thing you only think about when someone matters a lot.
The last line is the most interesting. The speaker wonders whether the other person is wondering back, and the line folds in on itself, with wondering about wondering. It suggests hope, but also uncertainty, since the speaker clearly doesn't know the answer. The mood is quiet, dreamy and a little vulnerable. The trailing dots after "smells" make it feel like the speaker's mind is drifting, and the poem ends on a question, leaving the longing unresolved.