At the time of his Paris exile, Mainzer became acquainted with the writings of psychoanalyst Wilhelm Reich.
Under the influence of Reich's ideas about sex-economy, Mainzer produced some major works on sexual coercion.
In 1941 Mainz continued his emigration, and went to the USA.
There he met his girlfriend Ilse Wunsch and lived for 25 years, "unmarried, in two different apartments, but in an intimate love relationship" until they married.
After his death in 1995 his wife established the Otto-Mainzer-Preis in New York for the science of love, worth 5,000 U.S.