Image Credit: WireImage Cooper Koch is off the market! The actor, who starred as Erik Menendez in Ryan Murphy's Monsters: The Lyle & Erik Menendez Story, revealed he is in a relationship during an interview on Watch What Happens Live with Andy Cohen. Monsters became the number one show on Netflix at the time of its release, according to Variety, bringing renewed attention to the Menendez brothers' case and the actors' performances.