The phrase "gnaws at" implies persistent and nagging discomfort, worry, or anxiety. Some synonyms for "gnaws at" include "plagues," "bedevils," "torments," "haunts," "preys on," "nags," "troubles," "worries," and "permeates." Each of these words infers a level of irritation or preoccupation with a particular thought or emotion. Whether it is a past regret, an unfulfilled desire, or a looming uncertainty, the feeling of something "gnawing at" us can be both distracting and unsettling. By identifying and acknowledging the source of this unease, we can work to alleviate its hold over us and regain a sense of peace and contentment.