Influence on Jules et Jim

https://fr.wikipedia.org/wiki/Jules_et_Jim_(film) go to point 8.3

Sorry I did not find a source in English.

It basically says that François Truffaut was obsessed by Design for Living (called Sérénade à Trois, in French), sometimes watching it three times in the same week.

Even if the story comes from a book, it's probably his love for the Lubitsch film that made him do Jules et Jim, one of his classics.