The speaker begins in a dark place. They hate themselves, even their own body, and feel squeezed between a sky above and a hell below, as if there is no good place left to stand. Strangely, they say they long to be trapped in their own nightmare, somewhere they can go nowhere. That wish suggests exhaustion more than courage: if nothing can change, nothing can hurt more.
Then the poem turns with "Only until you came." The phrase is a little broken, which fits the sudden shift. The unnamed "you" changes everything with two simple images. Salt becomes sugar, so something sharp and painful turns sweet. Wounds become stars, so the speaker's pain becomes something that shines. The title's "fallen angel" and the word "stars" frame this nicely, hinting at someone who has fallen but isn't ruined.
The mood moves from bleak and heavy to tender and hopeful, with gratitude at the end.