R&B singer-songwriter Muni Long has delivered heartbreaking news to fans, announcing her exit from Brandy and Monica's "The Boy Is Mine Tour." The sudden departure is due to a persistent and debilitating health crisis, as Muni Long's lupus battle made continuing the demanding tour schedule "unsafe." Source: Unique Nicole / Getty According to Hollywood Unlocked, the chronic condition has plagued Muni throughout the tour, which began in October. She had already missed several stops, with fellow songstress Mya filling in during her absence.