So This Is Paris (1926)

Georgette lives in Paris with her unexciting, effeminate husband, Maurice. Suzanne lives across the street, spending her time reading romance novels, while dreaming of someone more exciting than her own lackluster spouse, Paul. Both women happen across the other's husband, and they begin their dream affairs. Four people, each cheating on their spouse, none of them aware that their own spouse is cheating - who will tire of the 'excitement' first, and how?