If you loved Le Décalogue 3, tu respecteras le jour du Seigneur, try Brève histoire d'amour
Un pont entre un film que tu as déjà vu et un que peu de gens ont croisé. Voici ce qu'ils partagent, et ce que le second fait que le premier ne fait pas.

Le Décalogue 3, tu respecteras le jour du Seigneur

Brève histoire d'amour
Ce qu'ils partagent
Both films are directed by Krzysztof Kieślowski, and they both carry the bittersweet, tender mood tags, and they sit in Drama / Romance territory. If that's the register that drew you to Le Décalogue 3, tu respecteras le jour du Seigneur, the second film will land in a comparable space — through a different lens.
What Brève histoire d'amour is
Here's a film to either inspire or deter your inner voyeur. Tomek, a lonely post office worker, becomes infatuated with his neighbor, Magda, and spies on her. When they finally meet, the film suggests they have more in common than expected. It's certainly a comment on intimacy, of some kind.