Dorothea is miserable over the fact that Casaubon refused to acknowledge Will. Her life feels empty, as she cannot do anything to truly please Casaubon. She can’t see Celia, who is resting after having just given birth to a baby. That Sunday night after dinner Casaubon suggests they go to the library, where he asks her to read a document to him and make notes that he requests. Later, she finds Casaubon wrapped in a blanket, and asks if he is ill. He says he is simply uncomfortable and asks her to read to him.
Dorothea is in a truly miserable position here. She cannot see the man she truly loves (although note that she has not yet admitted to herself that she loves Will), but even her efforts to be loyal to her husband are not rewarded. They are instead met with indifference and scorn.
Before he goes to sleep, Casaubon asks Dorothea if she will promise to act according to his wishes after he dies. She is uncertain about making the promise before knowing what those wishes are, and asks that he give her some time to think about it. Casaubon falls asleep, but Dorothea is kept awake by her thoughts. She expects that Casaubon sees her as the last hope that his scholarship will actually be published. She is hesitant to agree to keep working on it after his death, as she finds it hard to believe that the project will ever amount to anything.
When Dorothea first got married, it would have been her dream come true to be asked to finish working on Casaubon’s manuscript after his death. This way she would truly have been able to live out her dreams through him. However, now that her illusions about his scholarship have been shattered, the dream no longer holds up.
At the same time, Dorothea cannot bear the cruelty of denying his request. Tormented, she is not able to fall asleep until the morning. Upon waking she goes to see Casaubon in the library, and he tells her that he doesn’t feel well and is going to take a walk outside. First, however, he asks if she has an answer for him. Dorothea doesn’t reply, but asks if she can meet him outside momentarily; Casaubon agrees and leaves. Dorothea intends to agree to his request, even though this decision makes her very sad and weary.
Dorothea’s absolute loyalty to her husband, though painful to witness, is admirable. Unlike other characters in the novel, she accepts responsibility for her bad decision (marrying Casaubon) and knows that she must live with the consequences.
Eventually Dorothea reluctantly goes out to meet Casaubon in the garden. She finds him sitting at a bench, seemingly asleep. She tells him that she is ready to give him an answer, but he doesn’t respond. Beginning to panic, she tries to wake him and fails. Casaubon is dead. Later, Lydgate sits with her while she talks hysterically, apparently in denial about her husband’s death. She asks Lydgate to convey messages to Casaubon, declaring that she is ready to make her promise.
The dramatic timing of Casaubon’s death means that Dorothea feels a deep burden of responsibility not for his passing, but for failing to give him the peace of mind that she would comply with his wishes after he was gone. This guilt manifests in her hysterical denial of Casaubon’s death.