The speaker looks back at who they used to be and compares that person with who they are now. Each stanza pairs a happy "then" with a painful "now." They once watched the stars, and now they draw the curtains against the light. Their eyes used to sparkle, but now they bite their lip to hold back a scream. Their smile, which came so easily, has turned into a groan.
The poem never says what caused the change. The second line hints that the old happiness came from being naïve, as if innocence has been lost and the speaker now sees things too clearly to feel carefree. The mood is heavy, quiet, and bitter. The short, steady lines and the neat rhymes feel almost controlled, which makes the suppressed pain stand out more. Shutting out the light suggests the speaker is withdrawing, and the poem ends on a note of hurt rather than hope.