Watch: 'Yellowstone' Delivers Another Shocking Death, As Kevin Costner's Character Demise RevealedThe Yellowstone spin-off is already leaning into heartbreak. During the March 1 premiere episode of Marshals, previously known as Y: Marshals, Luke Grimes' Kayce Dutton revealed his wife Monica Dutton, played by Kelsey Asbille, had died when he visited her grave. "I miss you, baby," Kayce says in the episode. "I miss my wife-my best friend. My only friend." Throughout the episode, Kayce and his son Tate Dutton (Brecken Merrill) alluded to Monica's death while hinting at her suffering.