Devil in the Flesh, Raymond Radiguet

It's wartime. The year is 1917. Marthe is 18. She's engaged to Jacques. Jacques is at the front. Then François, a young high school student, falls for Marthe, and Marthe falls into François's arms. They become lovers. In the distance, sometimes, the cannon roars.
As the narrator says in a youthful provocation, for teenagers at the time, the war on the home front was "four years of great holidays." You can read this 1923 book by thinking of the romantic and scandalous couple formed by Gérard Philippe and Micheline Presle in Claude Autant-Lara's 1947 adaptation. You can also read it by not believing Radiguet ("Everything is false") and keeping in mind that the author, as a teenager, had a lover named Alice, whose husband was at war. You can also see it as a sign that for women of all ages who seized the opportunity, this war was a time for a real questioning of a certain model of conjugality.
As Freud wondered in Psychology of Love Life, why are men so often excited by women who are already "taken"?