It is twenty-five years after the Archers' dinner party for Ellen. Archer is reflecting about the past in his library. Their eldest son, Dallas, had been born, followed by Mary, who has married a son of Reggie Chivers, and their youngest, Bill. Dallas is artistic and is training to be an architect. Archer is known as a model citizen of New York and a philanthropist, and has made a foray into politics. He was a dutiful husband to May until she died of pneumonia, and had honestly mourned her death. He feels that he has missed out on "the flower of life" (p. 296), but now thinks of Ellen only as one might think of an imaginary beloved in a book or picture, as a symbol of all he has missed.
May died believing the world to be a good place, full of harmonious and loving households like her own. But she was unaware that things had changed around her, and even her own children had concealed their views from her, just as Archer did his.
There is little left of the restrictive old New York, to the extent that Lefferts's sneering prophecy of years before that if things went on at this rate, their children would be marrying Beaufort's bastards, has come true. Dallas is marrying Fanny Beaufort, and no one objects. After his wife's death, Beaufort had married Fanny Ring, and had gone to live abroad. Young Fanny is the offspring of their union.
People now are too busy with reforms and fads to worry about what their neighbors are up to. Young people take it for granted that they will have what they want, whereas Archer's generation took it for granted that they wouldn't.
Dallas persuades his father to accompany him to Europe. In Paris, Dallas arranges for them both to visit Ellen. Dallas asks his father whether Ellen wasn't the woman he would have given up everything for - but didn't. The son says that the day before May died, she told Dallas that she knew the children would be safe with Archer, "because once, when she asked you to, you'd given up the thing you most wanted." (p. 304). Archer, moved that May had guessed his feelings and pitied him, replies that she never asked him.
Archer does not go with his son to visit Ellen. More than half a lifetime divided them, and he has no idea how she may have changed or whether she is living with someone. He asks his son to tell Ellen only that Archer is old-fashioned. He sits on a bench and looks up at her balcony, and thinks, "It's more real to me here than if I went up" (p. 308). A manservant comes out onto the balcony and closes the shutters, and Archer walks back alone to his hotel.
Wharton breaks with the tradition of romantic novels in her inconclusive ending. There is nothing to prevent Archer and Ellen from being reunited; even society has moved on from the restrictions that had previously bound them. If they were reunited, they would either find that they had changed too much and had nothing in common, or they would at last be together. But neither resolution occurs. The reader is likely to feel frustrated and dissatisfied, exactly as Archer and Ellen have felt over their unconsummated affair.
Critics have given different interpretations of why Archer refuses to go up and see Ellen. Some see it as a brave and wise decision; others as cowardice. Wharton tells us that Archer would rather hold on to the memory of Ellen than have 'real life' impinge on his own reality and, perhaps, destroy it. But the effect of the ending is to cast an extremely ironic light on what has gone before. Archer has struggled and fought against the societal restrictions that disapproved of his union with Ellen - though never resolutely enough to break through them utterly. Now, those restrictions have melted away, yet Archer still cannot reach out and embrace the love that has dominated his life throughout the novel. It is clear that the prison was not so much an objective reality as a creation of the minds of society people like Archer. It is like an agreement between the members of a club. Archer has imprisoned himself, and continues to do so, rather like a guinea pig who is so used to living in a cage that he will not leave it even when the door is left open. His half-hearted attempts to escape showed an irresolution that measured poorly against even May's single-minded determination to preserve her marriage against the incursion of Ellen.