In her 1855 fictionalized autobiography, Mary Gove Nichols told the story of her emancipation from her first unhappy marriage, during which her husband controlled her body, her labor, and her daughter. Rather than the more familiar metaphor of prostitution, Nichols used adultery to define loveless marriages as a betrayal of the self, a consequence far more serious than the violation of a legal contract. Nichols was not alone. In Unfaithful,...