A speaker is left broken by someone who promised, or seemed to promise, to stay. The poem opens with a question that is half accusation, half confusion: why was I so sure you would come, stay and remain? The three near-synonyms in that last line sound like someone pleading, trying to pin a person down with words.
The second stanza is more painful. The speaker says they were torn in half, and that the other person then set fire to their "most flammable parts," meaning the places that were most vulnerable and easiest to hurt. It feels like a betrayal of trust, aimed exactly where it would do the most damage.
The ending shifts. The speaker wonders whether they were meant to be burnt to ash and scattered, only to become whole again. The word "perhaps" keeps this hope uncertain. The mood is raw and grieving, but a faint sense of renewal, of rising from ruin, glows at the close. The word "bum" in the final stanza looks like a typo for "burn," so I've read it that way.