The couple, who costarred in the movie Adult World, walked their first joint red carpet at the InStyle and Warner Bros. afterparty. Roberts, 21, looked ladylike in a corseted tulle dress, while Peters, 25, cleaned up in a three-piece suit.
Later that evening, the Scream 4 actress and the American Horror Story: Asylum actor were seen "making out" at Sunset Tower, a source tells Us Weekly. "At one point Evan was sitting on Emma's lap as a joke."
Roberts -- whose ex-boyfriends include Chord Overstreet and Alex Pettyfer -- is "so in love" with Peters, an insider reveals. "Evan dotes on Emma -- he's always holding her hand. . . They are super cute together!"
Says a Roberts source, "I've never seen her so happy with a guy. . . Emma and Evan really support each other, one hundred percent."