Olive Smith does not trust anything she cannot measure, which is why the most reckless thing she does in The Love Hypothesis is turn a relationship into a test. To convince her best friend that she has moved on from a shared crush, she kisses the first man she finds in the corridor — Adam Carlsen, the professor the entire biology department has learned to fear — and then asks him to keep the fiction going. She is a scientist designing an experiment, and she has forgotten to account for the one variable she can never control, which is herself.

That is the engine of Prime Video‘s adaptation of Ali Hazelwood’s 2021 novel, a romantic comedy about two people who would rather run a controlled trial than admit to a feeling. Lili Reinhart plays Olive, a third-year PhD candidate whose research is real and whose social life is a rounding error; Tom Bateman plays Carlsen, whose reputation for dismantling colleagues in seminars is exactly why no one believes Olive would go near him. The arrangement suits them both — she gets cover, he gets the appearance of the local ties his department wants to see — and the comedy comes from watching two researchers treat courtship as a protocol, with terms, boundaries, and an agreed end date.

It matters that Claire Scanlon is directing, because this is the second time she has built a film around a manufactured relationship that outgrows its own contract. Her Set It Up, in 2018, took two overworked assistants who engineer a romance between their bosses and discovered the machinery turning on the people operating it; The Love Hypothesis hands the contrivance to the couple themselves. Scanlon works in the register of the screwball two-hander — timing, verbal sparring — rather than spectacle, and the fake-dating device she favours is the oldest trick the genre owns: a pretext that forces two antagonists into proximity until proximity does the rest. What is new here is that the pretext is written in the leads’ own professional vocabulary. When scientists talk about a hypothesis, a control, a confounding variable, they are describing a way of holding the world at a safe distance until it can be proven. The film borrows that language and then removes the safety.

The lineage is easy to place. The modern fake-dating comedy runs from the Netflix YA machine — To All the Boys I’ve Loved Before turned a contract romance into a template — through the theatrical enemies-to-lovers of Anyone But You, and The Love Hypothesis inherits both the beats and the fandom expectations that come with an adaptation. Hazelwood’s novel began life as Star Wars fan fiction and became a BookTok phenomenon almost single-handedly responsible for making STEM-set romance a commercial category. That origin carries an audience that owns Olive and Adam before a single frame exists, and it carries a subject the book never hides: the attrition of women in academic science, and the power gradient between senior male faculty and the junior women whose careers they can make or end. A rom-com has to hold that lightly, but the premise keeps it in the room — the joke only works because the imbalance is real.

Reinhart, stepping out of the long shadow of Riverdale, is cast against the type that made her, and she also executive-produces, a sign of how deliberately this was built as her vehicle. Bateman, known for the coiled menace of Behind Her Eyes and a turn in Murder on the Orient Express, is playing against his own register too: the fearsome professor whose severity turns out to be the least interesting thing about him. Around them, Rachel Marsh is Anh, the friend whose happiness sets the whole deception in motion; Jaboukie Young-White and Nicholas Duvernay fill out the lab-and-friendship world that a campus romance needs to feel populated. Sarah Rothschild wrote the screenplay, adapting a first-person novel whose interior monologue — Olive narrating her own feelings as if reviewing someone else’s data — is the hardest thing to translate to screen and the thing the film lives or dies on.

For Prime Video the release is also a strategy. After The Idea of You in 2024 and the streaming afterlife of Anyone But You, the platform has been quietly assembling a romance slate aimed at exactly the readership Hazelwood commands, and it is dropping The Love Hypothesis globally on a single day rather than territory by territory — the standard play for a title that wants to be an event before the discourse can get ahead of it. The bet is that a BookTok readership converts into a viewing weekend, and that a genre which reliably tops streaming charts can carry an adaptation whose fans will be counting the beats.

What the film cannot settle — what no version of this story settles — is the question its own premise raises. If a feeling arrives inside a contrivance, on a schedule both parties agreed to in advance, is it a result or an artefact? Olive would know the difference in the lab. The Love Hypothesis is interested in the moment a scientist realises she has run an experiment she can no longer read objectively, because she has become part of it. The happy ending the genre promises cannot certify which reading is true; it can only decide to stop asking.

The Love Hypothesis begins streaming worldwide on Prime Video on 23 September 2026. Directed by Claire Scanlon from a screenplay by Sarah Rothschild, and adapted from Ali Hazelwood’s novel, it stars Lili Reinhart and Tom Bateman, with Rachel Marsh, Jaboukie Young-White and Nicholas Duvernay.