Fingernails, a sci-fi romcom coming to Apple TV Plus from director Christos Nikou, imagines a future where one very specific technology has changed the world. In this timeline, scientists have figured out how to conclusively determine if two people are in love. This upends relationships as we know them, with couples sticking steadfastly to the results of the test; if they get a negative result, they end up splitting up. It’s a cute conceit for exploring the ways relationships can grow stale or change over time, and Fingernails builds on that with its darkly comedic vibe. It also has a surprising amount of body horror — the nature of which you might be able to glean from the title.

The film centers on Anna (Jessie Buckley), a teacher who is in a long-term — and test-approved — relationship with her boyfriend Ryan (Jeremy Allen White). They’ve reached the comfortable phase of their relationship; things aren’t exactly exciting anymore, but it could be worse than cuddling on the couch and watching documentaries every night. Plus, science has assured them that they’re meant to be together. Things take a turn when Anna starts a new job at The Love Institute, which not only performs the aforementioned love tests but also offers a series of lessons to prep couples for success. For reasons that aren’t made entirely clear, she keeps this new gig a secret from Ryan.

The Love Institute is like a business founded on the principles of Nora Ephron films. The waiting room is consistently filled with the sound of falling rain because it induces romance, while the lesson plans involves sniffing out your partner in a crowd, shocking yourself when they leave the room, and watching a steady diet of Hugh Grant movies together. Oh, and then there’s the test itself. If you haven’t guessed yet, it works like this: researchers pull off a fingernail from each person, and then place them in a giant retrofuturistic microwave to be analyzed. The whole thing only takes a few minutes but leaves a physical reminder that the test took place. Despite all of the fingernail pulling going on, love blossoms between Anna and her new co-worker Amir (Riz Ahmed) as they spend their days trying to help couples survive the test.

Now, I have a few questions about the world of Fingernails. It’s never really made clear why people put so much stock in this test. Married couples divorce after a negative result; families are broken up because of a simple test. Some people take it multiple times to be sure despite the fact that — and it bears repeating — you have to have a fingernail pulled off as part of the test. In the case of Anna, as she slowly becomes infatuated with Amir, she questions her feelings even more because science says she should be with Ryan. It’s a big thing to not explain because the test is the motivation behind pretty much everything that happens in the movie.

You need to put those questions out of your mind to fully enjoy Fingernails — it’s also good to not overthink when exactly the movie takes place, with its futuristic love test and otherwise very retro setting, one that seems completely devoid of smartphones. But it’s worth it because it’s the kind of slow-burning, darkly funny romance that’s pretty rare. The gruesomeness of the test is contrasted by the ridiculousness of the love training; at one point, a researcher wonders aloud if setting a theater on fire during a Hugh Grant marathon would inspire an even deeper connection. And the stars at the heart of the love triangle all put in strong, believable performances that — despite a seemingly predictable setup — had me guessing how things would finally end up.

Ultimately, the worldbuilding, vague as it is, serves largely as window dressing for a straightforward yet well-crafted story about how relationships evolve over time. It’s sweet and funny and occasionally grotesque — the rare romantic comedy that might make you wince.