The Honeymoon Killers (1970)

In the early 1950s, Martha Beck, who lives with her slightly senile mother, is the head nurse in a Mobile, Alabama hospital. She is bitter about her life, she not having male companionship in large part because she is overweight, while her bitterness in turn does not endear her to people. She is initially angry with her best friend, Bunny, for signing her up to a lonely hearts club, but eventually decides to give it a try. Through it, she meets Ray Fernandez, a suave Spanish immigrant living in New York, he who contacted Martha as the first through the club. After Ray's trip to Mobile to meet Martha, they fall in love. Upon a subsequent visit Martha makes to Ray in New York - which leads to her being fired in part for her time off work - he decides to be up front with her: that she is not only not his "first" but that he is really a con man who, primarily through the club, seduces then bilks lonely women of their money. Pretending to be his sister to prospective targets, Martha decides to join Ray on his cons as they travel the country together. Their differences in style causes problems, Martha who is more direct, more impatient and more violent, she who is the first to consider killing to get what they want. But what has the potential to be the primary cause of their downfall is Martha's jealousy over Ray even pretending to seduce other women, let alone any time he may have sex with them.