Alissa Violet -- a popular YouTuber -- has been arrested after she allegedly got into a ferocious argument with her boyfriend ... TMZ has learned. Sources tell TMZ ... Alissa and Ryan Pownall went back to his apartment in Hollywood after a night out drinking at a local bar at the end of February. When they got to the apartment, our sources say Alissa and Ryan -- who were both allegedly intoxicated -- got into an argument about Ryan's phone. Alissa left the apartment for a time, sources tell us,