This chapter examines military attitudes toward “emotional injuries” resulting from the end of romantic relationships. Evaluations of why some men “cracked” evolved substantially from World War I to the present. Often, however, psychiatrists attributed servicemen’s maladies to deficient female love: whether that of mothers or romantic partners. In Vietnam, psychiatrists construed romantic rejection as a “narcissistic injury”: a blow to the ego that led men to decompensate in various ways. Alcoholism, going AWOL, self-harm, and violence directed toward others were all associated with Dear John letters. The chapter considers how the military medical and legal establishments adjudicated unlawful acts perpetrated by servicemen whose intimate relationships had recently been severed by letter. It focuses on two court-martial cases: a Korean War POW who briefly rejected repatriation to the United States in 1953, citing a Dear John as his motive for defection, and a Marine Corps private court-martialled in 1969 for killing four Vietnamese peasants. In the latter case, military lawyers deemed the defendant to have been temporarily insane after his fiancée sent him a Dear John.