As the title might suggest, An Ideal Husband's primary theme is marriage, a common premise for the potboiler melodramas of Wilde's day. To recall our discussion of the play's Context, the Victorian popular theater provided stock storylines of domestic life that, after various crises, would culminate in the reaffirmation of familiar themes: loyalty, sacrifice, undying love, forgiveness, devotion, and onward. More often than not, this reaffirmation also involved the re-establishment of the conjugal household.
Though An Ideal Husband adopts these motifs, it also mocks, parodies, and ironizes them with its more decadent and dandified characters. Thus we can organize the play's treatment of marriage according to the "poles" these characters might represent.
Lady Chiltern, for example, would predicate marital life on worship, posing her husband as a pristine ideal in both public and private life. Notably this love is explicitly gendered as "feminine." As the play progresses, Lady Chiltern's love comes to appear unreasonable and—once Sir Robert's secret sin is revealed—dangerous to the health of the domestic household. This opinion emerges most explicitly from Sir Robert and Lord Goring, who offer a competing model of marital love that the two identify as "masculine." If a woman loves in the worship of an impossible ideal, a man loves his partner for its human imperfections; his love includes charity and forgiveness whereas the woman's does not.
Thus the play calls for the tempering of the woman's overly idealizing and morally rigid love for one that can pardon human fault. Somewhat paradoxically (but all too unexpectedly), it will ultimately assign the role of pardoner to the woman; as Lord Goring tells Lady Chiltern in Act IV, "Pardon, not punishment, is [women's] mission" in love. Thus the play, miming a conventional narrative arc of the Victorian popular theater, in some sense ruins the ideal husband only to win his forgiveness from his virtuous wife. Re-establishing the conjugal household, this resolution numbers among the more sentimental and conservative of Wilde's day. Obviously, its gender politics are unfortunate to say the least.
The main obstacle to this reconciliation of married life, Mrs. Cheveley, the play's villainness, would subordinate and reduce to marriage to mercenary transactions. Schooled in Baron Arnheim's gospels of power and wealth—gospels that privilege the domination of others over all else—she has no qualms blackmailing Sir Robert and potentially destroying his conjugal bliss to secure her financial investments. Moreover, we come to learn that she engineered a false courtship with Lord Goring in their youth to swindle him out of a settlement. Finally, she will offer to exchange her evidence against Sir Robert for Goring's hand in marriage; Goring will then roundly condemn her for defiling the ideas of love detailed above. With these offenses in mind, Mrs. Cheveley's ultimate capture by a stolen wedding present—the diamond brooch—would revenge her crimes against marriage.
In contrast to both the Chilterns and Mrs. Cheveley, however, the play features a number of characters and conversations—especially those involving "banter" and other apparently frivolous speech—that mock its more conventional thematics. In particular, Goring and Mabel Chiltern function as foils to the upstanding Chilterns. Throughout the play the pair assume an amoral pose, disparaging the demands of duty and ironizing social convention. Notably then do the penultimate lines of the play, spoken by Mabel Chiltern upon accepting Goring's proposal, dispense with the notion of ideal husband altogether. "An ideal husband!" she exclaims. "Oh, I don't think I should like that. It sounds like something in the next world." Goring is to be what he wants while Mabel would only be a "real wife." In this sense, Mabel and Goring playfully reject the moral thematics described above, unconcerned with the question of what a man and wife should be ideally.