In Harry Potter and the Deathly Hallows, Ron's feelings of doubt, envy, and insecurity about Harry were intensified due to an object known as the Horcrux. This Horcrux took the form of a locket and affected Ron by bringing his worst emotions and self-doubts to the surface, creating moments of friction between him and Harry. Ultimately, this led to their temporary estrangement during their search for Horcruxes. Later, Ron returned, acknowledging his mistake and reuniting with Harry and Hermione to finish their dangerous mission.