Over the next two months, David continues to live with Miss Betsey and pay visits to Agnes, whose encouragement he relies on heavily in his work. At the same time, however, he finds these visits painful, since it reminds him of the kind of marriage he could have had. He is still determined not to risk their relationship or her happiness by confessing his love, although he does fantasize about telling her the truth as an old man. Meanwhile, Miss Betsey seems to understand David's dilemma, but never speaks to him about it. As Christmas approaches, however, David begins to worry that Agnes has not told him to who she is in love with because she has guessed his own feelings. Since this would make his restraint pointless, he decides he needs to broach the topic with her.
In many ways, Agnes is already serving as a wife to David; her support of his writing career, for instance, resembles Sophy's clerking for her husband Traddles. David, however, is so humbled by his past romantic mistakes that he doesn't see this, and even assumes that Agnes is in love with someone else.
One day, Miss Betsey asks David if he is going to Canterbury to read his manuscript aloud to Agnes. He says that he is, and then asks whether his aunt knows anything more about Agnes's "attachment." Miss Betsey, looking at David with "a kind of doubt, or pity, or suspense," says that she does, and that she believes Agnes is going to marry soon. David, attempting to look happy, blesses Agnes, and Miss Betsey echoes this, blessing her future husband as well.
Once again, David fails to realize that his aunt is talking about him when she says Agnes is likely to marry soon.
After a long, cold ride, David arrives at the Wickfields' to find Agnes done teaching for the day. They discuss David's work and Agnes, who is busy stitching, jokes that she needs to enjoy David's company while she can, because he will soon be too famous to talk to her. David, however, grows serious and asks Agnes whether she doubts his loyalty to her. She says that she does not, and David, reminding her of his deep gratitude to her, asks her to share her "secret" with him. Agnes says nothing, and David presses her to "let [him] be [her] friend, [her] brother." At this, Agnes gets up and walks across the room, starting to cry. David begs her to tell him what's wrong and let him help her, but she says she can't speak at the moment.
David unwittingly hurts Agnes by describing her as his sister and therefore insisting on the platonic nature of their relationship. David does this, of course, because he is trying to hide his own romantic feelings for fear of hurting Agnes. With that said, it's striking that David so often describes Agnes as his sister. On the one hand, this seems to give the relationship an incestuous subtext that's problematic elsewhere in the novel—for instance, in Dora's resemblance to Clara Copperfield. These other matches, however, tend to resemble parent-child relationsips, and are questionable in part because they signal an unwillingness to leave childhood behind.
David begins to suspect that Agnes might be in love with him, but is afraid he is letting his hopes run away with him. He assures her that he has learned enough over the years not to "envy" her love for someone else, but Agnes simply tells him that he is mistaken: she has a secret, but it is not a "new one," or one that she can tell David.
David's restraint and his willingness to support Agnes in spite of his own feelings contrast with his jealousy while courting Dora, and therefore demonstrate his growth as a character.
Agnes tries to leave, but David catches her and says that he never planned to tell her this, but that he now hopes that he might one day be something other than a brother to her. Agnes continues crying, but David presses on, explaining that she was always so selfless, that he learned to take her for granted. Nevertheless, he says, his life even with Dora would have been "incomplete" without Agnes. After Dora's death, this became even clearer to him, and he has loved Agnes ever since. David then explains why he has stayed silent, and how grateful he would be to be Agnes's husband. Agnes accepts, and David senses that Dora is speaking through her and blessing the union. Agnes, meanwhile, says that she is very happy but has one thing to confess: she has loved him "all [her] life."
Ironically, the selflessness that makes Agnes such an ideal wife for David is also what caused David to overlook her for so long. Although this double bind is eventually resolved, it points to one of the many tensions present in nineteenth-century gender norms. Another issue the novel works to resolve here is David's prior marriage to Dora—in this case, by suggesting that Dora herself has blessed the marriage from beyond the grave. Although it later emerges that Dora did in fact give Agnes permission to marry David, readers may find this particular passage strange or even troubling; David's suggestion that the moment inspires him "tenderest recollections" of Dora implies that Dora was just a stepping stone on the way to marriage with Agnes.
David and Agnes go for a walk that evening, and the quietness of their surroundings seems to mirror their own "blessed calm." David thinks back over his whole life, imagining a "ragged way-worn boy" who has finally arrived at this destination.
In retrospect, David suggests, everything that has happened to him has led up to and prepared him for his engagement to Agnes. Regardless of whether this is true, it's certainly the case that David's memoir structures his experiences in a way that frames even apparent mistakes or dead-ends, like his marriage to Dora, as necessary parts of his development.
The next day, David brings Agnes with him to see Miss Betsey, but does not immediately reveal that they are engaged. After dinner, however, David says that he has talked to Agnes about the conversation he had with her. Miss Betsey scolds him for breaking his promise to keep quiet, but David insists his aunt shouldn't be angry, taking Agnes's arm to demonstrate what he means. This sends Miss Betsey into "hysterics," and Peggotty needs to revive her. Miss Betsey then hugs Peggotty and Mr. Dick, telling them the good news. She refuses to tell David, however, whether she deliberately told him Agnes was going to marry in order to provoke a confession.
Miss Betsey's emotional response to the news of Agnes's and David's engagement is yet another sign that she isn't actually as unsentimental as she pretends to be. She's clearly very savvy, however, since Dickens strongly implies she was working behind the scenes to nudge David towards proposing.
David and Agnes marry about two weeks later, with only Traddles, Sophy, Doctor Strong, and Annie Strong as wedding guests. As the couple drives away together, Agnes says she has something she needs to tell David: the night Dora died, she "left something" to Agnes, and Agnes asks David to guess what it was. Agnes confirms that Dora insisted that only Agnes could succeed her as David's wife. The couple embraces, weeping but very happy.
Agnes's confession confirms David's earlier sense that Dora approved of their marriage. In this way, it mitigates any uneasiness readers might have about David remarrying, and also recasts David and Dora's marriage as useful rather than mistake, in the sense that it helps bring Agnes and David together.