McEvoy was married several times, taking his first wife in 1940. Beatrice Cartwright, a member of the Pratt family and heir to a fortune from Standard Oil, was twice his age and had lived with McEvoy for several years before their marriage. The union did not last, and in 1942 Cartwright accused McEvoy of being unfaithful with "three well-known society women". The divorce was granted on the grounds of misconduct. McEvoy was not present for the decision as he was embroiled in a statutory rape case that had been opened against close friend Errol Flynn. 17-year-old Betty Hansen had accused Flynn of committing the offence during a party at McEvoy's Bel Air home, but McEvoy continued to publicly defend Flynn.