An 1895 play by the inimitable Oscar Wilde, considered one of his best, that was made into a rather good movie in 1999 by Oliver Parker. (There was also a film version in 1947 which was apparently very good, but I haven't seen it.)
Set in 1890s London, the story concerns the principled politician Sir Robert Chiltern (Jeremy Northam in the film version), his righteous wife Gertrude (Cate Blanchett), his witty sister Mabel (Minnie Driver), his caddish friend Lord Goring (Rupert Everett), and the scheming Mrs. Cheveley (Julianne Moore). Sir Robert and his wife are very much in love, but her vision of him as the epitome of high morality is shattered when her high school nemesis Mrs. Cheveley sweeps into town, for she has in her possession a letter that exposes a shady deal Sir Robert made in his younger days. She blackmails him to support a canal project in South America, and when a distraught Gertrude gets a whiff of the scandal she throws her husband out. From there Machiavellian plot twists ensue, but everything is righted in the end: the Chilterns are reunited, and Mabel and Goring marry.
Oscar Wilde is the master of wit, and this offering does not disappoint, littered as it is with sharp verbal thrusts and ripostes. But it is more than just high comedy; it is also a morality tale about the politics of society, love, and capitalism. The movie departs - in some places significantly - from the play, but both are enjoyable in their own right.
And just who, you might wonder, is the titular spouse? To his wife, Sir Robert is the perfect husband, even in spite of his finally-revealed flaw. Goring's father, meanwile, threatens his son, as they walk down the aisle after the vows are exchanged, that he best be the ideal husband else he be cut off with but a shilling, to which Mabel retorts that she doesn't think she'd like an ideal husband anyway. So both are, or neither, in their own ways.
A quick Google search will reveal many sites with the full text of Wilde's play, if you wish to read it.