The Astonished Heart (1950)
Well, Noel Coward is above all a writer, and this is a sharp, well written, and contemporary (for 1950) drama. It is acerbic and witty, and it has a dry style you'd be forgiven for calling British (everyone else does) but it is most of all effective. And the story deals with that most basic of human dramas, falling in love when you shouldn't.
Coward was most of all a playwright, and he defines the sophisticated, dry, somewhat emotionally removed culture that was present in mid-Century London (and most of well off Britain). The particular material was originally a short play from 1935, and it actually still feels a little pre-War, not in any overt sense, but in its flavor, it's lack of feeling of post-war sensibilities in film as much as theater. But this isn't a bad thing--the play is about things outside of any one era. In fact, the much better 1945 movie "Brief Encounter" is also based on a short play from the same period, and deals with adultery, as well. And there is a reference to a pilot being shot down in the war, an adjustment made for the times.
By the way, adultery has always been in issue in classic (1930s-50s) movies when it butted up against the Hays code. In Britain, the "O'Connor" rules were something similar but were eventually more flexible. British movies did face American censors for release in the U.S., and the whole atmosphere of the commercial movie industry was to avoid getting into trouble. So the key result was that characters who did bad things had to meet bad ends.
Coward is a terrific actor in this kind of role. Like many actors of his generation, he plays the same kind of person in all this movies, but plays them (or it) so well that's all that matters. Of course, he's the main character in his own play, which is under his control. The two women around him, both little known to American audiences (the Celia Johnson is a wonder as his wife), are spot on perfect in those kinds of cultured London upper crust roles. All is well except love. They discuss their affairs with a kind of dispassion that makes the psychiatry dialog in the movie steamy by comparison. It's all very admirable and pathetic (by our more expressive standards) at the same time. And good movie material.
Never mind that the music is overly dramatic at times (Coward wrote the music, too!), or that it can be so talky it betrays its theatrical roots (as a play). This is a solid drama, and a serious one, and one many of us can relate to. And if "Blithe Spirit" or "Brief Encounter" are better entries to Coward's writing, this shows him as an actor extremely well.