The speaker has lost everything in a fire: possessions, creative work ("my melancholy art"), and the home they expected to live in until they died. The opening lines are plain and stripped down, as if the speaker is listing what's left after the loss, or what's gone.
The second stanza turns from the event to the way it gets told. The fire was an accident, the speaker admits, but "in the narrative" they tell themselves, there's a different feeling: "we might have done more." Then comes the surprising, tender line, "we might have spooned." That small image of closeness suggests the speaker is thinking of another person, perhaps a lover, and of intimacy that was missed or never fully shared. The poem doesn't say who "we" is.
The mood is hushed, wistful, and a little guilty. The title "Heat" connects the fire's destruction with warmth between two people, and the poem seems to wonder which one the speaker really regrets losing.