Matt Cohen, the Canadian writer, who writes a modernist outlook, realistically takes into consideration the Ontario ethos of Canada. He particularly deals with the family structure of patriarchal nature in which the legacy is transformed from one's father to his eldest son. Naturally in this structure women are marginalized, they are the 'outsiders' who are brought in for the sake of the contribution of the family line. Besides, women are mostly used by the men for the gratification of their sexual desires. Matt Cohen handles man woman relationships as one of the major themes in his novels and mainly explores extramarital relationships, where both men and women are aggressive. In the present paper, the attempt has been made to explore the same in Emotional Arithmetic. Though Melanie is married to David, she is not faithful to him. She has her extramarital relationship with Christopher Lewis, her earlier lover. On the other hand, including David, other male characters in the novel also have their extramarital relations with other female characters. Benjamin, son of Melanie Winters, is not faithful to his wife. He has affair with Julia Delphanso, a young nurse to his mother