Stewart's first interaction with his future wife, Gloria Hatrick McLean, was at Keenan Wynn's Christmas party in 1947. He had crashed the party and became inebriated, leaving a poor impression of himself with Hatrick. A year later, Gary Cooper and his wife Veronica invited Hatrick and Stewart to a dinner party, and the two began dating. A former model, Hatrick was divorced with two children. Stewart and Hatrick were married at Brentwood Presbyterian Church on August 9, 1949, and remained married until her death from lung cancer in 1994.