If you loved Decalogue III, try A Short Film About Love
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
What they share
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 Decalogue III, the second film will land in a comparable space — through a different lens.
bittersweettender
What A Short Film About Love 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.

