As Archer’s two love interests in the novel, May and Ellen act as foils for each other. May is a sheltered young woman from New York who has been trained by her mother from birth to be everything a man in their society supposedly desires—innocent, virginal, and well-mannered. In this way, she represents the conventional and respectable life Archer has himself been trained to desire. While he is initially drawn to May’s beauty and kindness, upon becoming engaged to her, he finds himself questioning if she can be the type of partner he really craves—one who can engage with him on topics such as art, culture, and worldly affairs.
Ellen, on the other hand, is able to offer Archer all of this and more. As a married woman from Europe, she has sexual experience as well as a passion for the arts and good conversation. She has seen far more of life than any of the young women in Archer’s social circle, traveling widely and fighting her way out of an unhealthy marriage (which was rare for women to do at the time). Though Archer initially tries to change Ellen to help her fit into his rules- and manners-obsessed New York society, he comes to love her for all of the ways she transgresses these rules.
It’s worth nothing that, by the end of the novel, Archer is forced to confront the assumptions he has held about both of these women. Ellen eventually comes to care about following the rules (as she refuses to have a sexual relationship with Archer and leaves New York when she finds out May is pregnant) and May comes to demonstrate that she is not as naïve as he believed her to be (as she manipulates Ellen into believing she’s pregnant before she actually knows that she is). In this way, the women start out as foils for each other but end up becoming complex characters in their own right by the novel’s end.