Just over a year after the film had its world premiere at the Berlinale Film Festival, Christian Petzold’s tragic romance “Undine” is finally available for streaming in the United States – and at the risk of being dramatic, if there’s one romance film you’re going to watch in 2021, make it this one. A modern reimagining of the European myth Undine (also spelled Ondine), the film reinterprets the story of a water nymph who is doomed to kill the man she loves if he’s unfaithful to her – a largely influential myth whose influence can be traced all the way through modern classics like Disney’s “The Little Mermaid”.

An animated musical “Undine” surely isn’t, though: swapping mystical water creatures for a grounded, almost sterile backdrop of Berlin, “Undine” is just barely on the edge of mysticism or magic realism – opting to let the viewer’s imagination do most of the heavy lifting when it comes to Undine’s mystic abilities and her fate. Instead of latching onto the more fairytale aspects, “Undine” latches onto the electric chemistry between Paula Beer (the titular Undine) and Franz Rogowski (Christoph, Undine’s lover).

The film further subverts original expectations by making the doomed romance not between a man who will eventually be unfaithful to Undine – but instead, the man who she meets almost immediately after being cheated on. The film’s cold open takes place just moments after Undine’s previous boyfriend Johannes (Jacob Matschenz) tells her he cheated – which allows for Petzold to have free reign of storytelling without being weighed down by the constraints of the myth.

Thus, as we slowly fall in love with Cristoph just as Undine does, Johannes’ betrayal (and his inevitable death at Undine’s hand) falls to the back burner, lulling the audience into a false sense of security where it’s almost easy to forget about Johannes entirely. It’s a testament to the power of Christoph and Undine’s love – because although the original myths centers around Undine and the man she’ll eventually kill as the main romance, Christoph being the main romantic prospect infuses a dire kind of uncertainty to the film. Yes, we know that (unless he also cheats) Undine won’t have to kill him – but there’s a nagging sense of dread that, given her history, there’s no way her pure, sickeningly-sweet romance with Christoph will end happily.

It works on its own conceptually, but the already strong premise is catapulted to perfection thanks to the sheer, unadulterated chemistry between Beer and Rogowski – they have the kind of charmingly imperfect and sickeningly sweet love affair that dreams are made of. Christoph (who works as a diver – another clever twist on the concept of a mermaid falling in love with a sailor) is awkward, genuine, and utterly charming – it’s easy to see why Undine falls for him so quickly after having her heart stomped on by Johannes.

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Though Franz Rogowski doesn’t fit the traditional idea of a leading man, he brings an endearing, indescribable quality to Christoph that can’t be forced or faked – a sort of charisma where you can’t help but smile at his bleeding heart approach towards romance, and devotion towards Undine. While Paula Beer’s leading performance as Undine may be the quietly devastating anchor that propels the film forward, it’s Rogowski’s magnetism that infuses the film (and their romance) with the vitality and energy which makes the inevitably tragedy of the ending all the more painful.

Granted, this isn’t a film for thrill-seekers or adrenaline-junkies: though it sits at a short but sweet runtime of an hour and 23 minutes, it still devotes a frankly surprising amount of its runtime to Undine giving long, detailed speeches at her job as a tour guide/historian. It’s a strange choice that gives the entire film a sort of disorienting quality, especially for English speakers: the film is in German, which means most American audiences will be using subtitles.

Still, despite (or perhaps because of) the obscenely long monologues about Berlin’s architecture, “Undine” has an ethereal, dreamlike tone and pacing that simultaneously makes the film fly by, while also letting the viewer savor every moment, every soft gaze and affectionate touch, of Undine and Christoh’s relationship.

The film’s already volatile emotional potency is heightened by its use of Bach’s adagio concerto in d minor, which serves as the musical theme for Undine herself throughout the film. It’s a haunting, delicate piano that tinges “Undine” with a persisting sense of dread, even when Christoph and Undine are in the brightest points in their relationship – a bitter reminder that their devotion will ultimately end in tragedy.

Grounded by a pair of flawless performances from Paula Beer and Franz Rogowski, Christian Petzold’s “Undine” is a gentle, bleeding heart romance that reimagines a classic myth with painstaking delicacy and affection. A masterclass in both acting and direction, it’s the kind of heartbreaking tragedy that will simultaneously leave you believing in love and heartbroken at the thought of losing it.