 The episode was written by series co @-@ creator Michael Schur and directed by Ken <unk> . " Galentine 's Day " featured a guest appearance by John Larroquette as Frank Beckerson , the long @-@ lost love of Marlene <unk> @-@ Knope , who was played by Pamela Reed . It also featured the last in a string of guest performances by Justin Theroux as Leslie 's love interest , Justin Anderson . 
