Karen Holmes (Deborah Kerr) is basically the most desperate of all desperate housewives: she hates her hubby, is bored out of her skull at home, is depressed that she can't have children, and basically is looking for a better life than the one she has… which probably involves a lot of Hawaiian-print decorating schemes.
However, Karen Holmes isn't just bored and lonely—her life has been nearly ruined by her terrible marriage to Captain Holmes. Holmes is a serial adulterer, cheating on Karen over and over again. It's through his drunken inattention that she loses her baby… and is told that she'll never conceive again.
After this tragedy, Karen starts to cheat on Holmes in return—which, you could argue, isn't really cheating, since Karen remains the one who's been totally and persistently betrayed. Sgt. Warden gets interested in Karen and stops by her place to hit on her—but he gets a bigger dose of "reality" than he probably bargained for. Warden tries out one of his (cheesy) pickup lines, and Karen hits back with a revealing speech:
WARDEN: No— it's just that I hate to see a beautiful woman goin' all to waste.
KAREN: Waste, did you say? Now that's a subject I might tell you something about. I know several kinds of waste, Sergeant. You're probably not even remotely aware of some of them. Would you like to hear? For instance, what about the house without a child? There's one sort for you.
Yowch. This grimmer-than-grim speech gets us every time.
An Affair to Remember
Warden and Karen continue to sneak around, at potential peril to them both—Warden could actually end up in prison for sleeping with an officer's wife.
Karen comes up with a plan: she's wants Warden to apply to become an officer, so she can divorce Captain Holmes and marry him (without losing any quality of life). But Warden is reluctant, as this doesn't really fit his self-image.
Karen's fate ends up being a tragic one. After Pearl Harbor, Warden definitively abandons any thought of becoming an officer, and Karen has to travel back to the mainland U.S. with her resigned, disgraced husband.
Yet she looks back on Hawaii wistfully from her ship. Maybe, when the war is over, she'll come back and do some more beachside smooching with Warden. Symbolically, it all depends on whether the flower garland she releases from the ship will float out to sea or back to the shore of Oahu.