After the death of her boyfriend, Cedric Diggory, at the Triwizard Tournament, Cho Chang was still suffering from the loss upon her return to school in September. Her increasing feelings for Harry did not help her troubled state of mind, and she quickly changed from being a popular, giggly girl into one who could be found more often than not crying in the toilets. She nevertheless joined Dumbledore's Army when it was set up and became an enthusiastic member, learning to master spells she had always struggled with before.