In St. Augustine, Archer is at first blissfully happy to see May. But as he listens to her prattle on about her simple daily activities, he finds his mind wandering. With the rest of the Welland family, the subject of conversation again returns to Ellen Olenska. May's mother blames the Countess's unconventionality on her eccentric European upbringing, and she thanks Archer for convincing Ellen not to sue for divorce. Archer is secretly annoyed, feeling that by not allowing her to divorce, the Mingott clan is ensuring that Ellen will eventually become the mistress of Beaufort rather than the lawful wife of some upstanding man.
Alone with May, Archer again presses her to shorten the length of their engagement. May surprises him by asking why he wants a short engagement. She wonders if it because he is not quite certain that he wants to marry her. She admits to Archer that since the announcement of their engagement he has acted differently toward her, and she is afraid that this is because he is still in love with his mistress of years past. May feels that if Archer is still in love, his passions for his mistress should come before his social obligations to May. Newland, caught off guard, fumbles in his speech, but manages to reassure May that is she that he loves. As soon as May is reassured, she returns to her usual complacency, and Archer is left wondering how she could act so assertively for the sake of others while remaining so passive in her own personality.
Upon returning to New York, Newland calls on Mrs. Mingott at her home. As they banter, Ellen appears and joins the conversation. As Archer leaves, he asks if he can visit her the next evening. When Archer arrives the next evening, he finds Ned Winsett, Medora Manson, and Medora's gentleman friend assembled in Countess Olenska's living room. After Ned leaves, Medora eagerly thanks Archer for persuading Ellen not to leave her husband. Medora relates that the Count Olenski wishes her to convince Ellen to return to him. Archer is horrified and vows that he would rather see Ellen dead than have her return to her husband. Medora, pointing to a bouquet obviously sent to Ellen by a hopeful suitor, asks Archer if he would prefer for Ellen to enter such illicit relationships.
At that moment, Ellen enters the room. She is instantly angered by the sight of the flowers and asks them to be given away. After Medora leaves, they discuss Olenski's request, which Ellen dismisses. They also discuss Archer's engagement to May and May's fears that there is another woman. Archer confesses that May is correct and that it is Ellen he would marry if it were possible for either of them. Ellen responds that it is Archer that has made a marriage between them impossible, for she had nothing to fear from Count Olenski's letter, and she decided not to sue for divorce only because Archer himself told her she should.
Archer is astonished. For a moment, he tries to convince Ellen that there is still time and that he can break from his engagement and she can divorce. She refuses, responding that it was Archer himself who taught her that one's personal happiness should never come at the expense of pain for others. Just then, a telegram arrives from May, stating that the Wellands have consented to push forward the wedding date.
In St. Augustine, Archer is once again disillusioned with May's naïveté and her rote opinions. Archer is afraid that May will, like her mother before her, be doomed to a life of "invincible innocence," in which she will stubbornly ignore that which is upsetting or unpleasant in order to maintain the same world outlook she has been trained to have. For a moment, Archer is shocked that May knows about his former mistress and that she wants him to reconsider their engagement. However, his disappointment soon returns, for he interprets her bold encounter as a selfless act designed to defend his former mistress and his own feelings. He comes to the conclusion that May is only capable of impassioned action when she is defending other individuals or the principles she has been trained to follow.