Answer

They are dead and forgotten, or so it seems. She is all alone ‘I shivered comfortless’ (line 25) and has no sense of presence here ‘but cast no chill across the tablecloth;’ she has not returned as an unpleasant ghost.

She feels ‘all forgotten’ (stanza 4) and ‘shivered, sad to stay’ she does not want to stay to see the happy scene, as she wishes she were still a part of it, or maybe is angry that they are not more sad to see her gone.