Robert walks in with the pink letter in his hands. Because the letter is not addressed, he assumes the letter is meant for him. He is overjoyed by his wife’s expression of love and trust, and she decides not to correct him. Lord Goring discreetly leaves the room. Robert tells Lady Chiltern that he no longer fears public disgrace, because he has her love. She happily informs him that Mrs. Cheveley gave his incriminating letter to Lord Goring: Robert is safe. He is overwhelmed by relief. He wonders whether he should retire from politics to amend for past mistakes, and Lady Chiltern encourages him to do so wholeheartedly.
Only a little while earlier, Robert assumed the worst of his friend Goring due to a misunderstanding. But he does not make the same mistake here: he assumes the best about his wife. And, on her end, Lady Chiltern realizes that she could have trusted her husband with the truth. At the beginning of the play, they were as distant and formal with one another as business associates. With Lord Goring’s help, they’ve learned to rely on one another.
Lord Goring comes back into the room, and Robert thanks him effusively. A servant comes in to announce Lord Caversham’s entrance. Lord Caversham congratulates Robert on his speech and tells him that Robert has been elected to a seat in the Cabinet. Robert is delighted by the news, but he tells Lord Caversham, with just a hint of regret, that he cannot accept the seat – he has decided to retire. Husband and wife leave to write a letter declining the position.
Robert is sincere in his desire to make things right with regard to the dishonest letter. But insofar as morality is simply an attitude that values personal relationships over most other concerns, it is not especially moral to resign – it does not benefit anyone. Robert’s unwillingness to resign is not a sign of moral flimsiness.
Goring sends his father to speak to Mabel in the conservatory. Meanwhile, Lady Chiltern reenters the room. Goring scolds her for encouraging Robert to decline the seat. She should not continue to punish him for the mistakes of his youth, he says; she should help him live the kind of life he wants – a busy, satisfying political life. That is her duty as his wife. “A man’s life is of more value than a woman’s,” he says; a man’s life is intellectual, and a woman’s life is emotional. She should not prevent her husband from leading the life he was destined for.
In fact, resigning would do nothing except hurt Robert. Though such an act has an appearance of “high moral tone,” as Goring calls it, it is essentially morally neutral. But it is wrong, and not neutral, for Lady Chiltern to encourage Robert to resign. She is encouraging him to sacrifice his own happiness at the altar of propriety (convention disguised as morality).
Robert comes in, carrying his letter of resignation. Lady Chiltern reads it and rips it up. Using Lord Goring’s own words, she tells Robert that she does not want him to sacrifice his career, and that it is her duty as a woman to forgive him – “that is how women help the world.” Robert thanks Goring for all he’s done. In return, Goring asks Robert for his sister Mabel’s hand in marriage. At first Robert does not grant it, thinking that Goring is in love with Mrs. Cheveley. But Lady Chiltern explains the whole misunderstanding – Goring was waiting for her, and not Mrs. Cheveley, the previous night – and Robert happily gives his blessing. Robert realizes the pink letter was meant for Lord Goring; as a symbolic gesture, Lady Chiltern writes Robert’s name in at the top of the letter.
It is clear, from this scene, that Lady Chiltern has learned to trust her husband a little better, because she does not hesitate to tell him the (potentially alarming) truth about the letter. Trust enables her to act selflessly in order to help her friend. The troubling implication of Lord Goring’s advice is that men achieve things, and women help men to achieve things. It is an explicitly sexist assertion, but one that is tempered by historical context. In turn-of-the-century England, when women did not even have the right to vote, women had few opportunities for independent achievement.
Lord Caversham and Mabel Chiltern enter the room. Lord Caversham is shocked and delighted by the news of the engagement, and also by Robert’s change of heart about the Cabinet seat. He threatens to cut Goring off if he is not “an ideal husband” to Mabel, but Mabel interjects to say that she would not like such a husband - she would rather be “a real wife.” Everyone but Robert happily leaves the room to go to lunch. A few minutes later Lady Chiltern comes looking for him. They promise to love one another, and to hold love above all things.
Men and women, in this play, constantly match wits – evidently, Wilde did not believe women were less intellectually capable. Perhaps if he had written about a society which offered equal opportunities to men and women, he would have portrayed love and marriage as a relation of equality as well: both husband and wife striving to be “real,” professionally happy, and mutually forgiving.