Warning: This article contains spoilers for The Love Hypothesis book and movie.
Hypothesis: It’s possible to make a film adaptation of a bestselling romance novel that readers will love.
While the results may vary, as with any book to movie adaptation, there are some key differences between Ali Hazelwood’s 2021 novel The Love Hypothesis and Prime Video’s 2026 rom-com starring Lili Reinhart and Tom Bateman, out Sept. 23
For those unfamiliar with the BookTok favorite, which began as Star Wars fanfiction, The Love Hypothesis follows PhD candidate Olive Smith (Reinhart) and Stanford University professor Dr. Adam Carlsen (Bateman), who, after an impulsive kiss, form a fake relationship and pretend to date.
And though some characters and scenes are altered for the film, don’t worry, romance readers—not only is chapter 16 in the movie, but it is not watered down. (The movie is rated R, after all.)
To see what actually did change, grab your lab coat and goggles—and read on for a deep dive into the biggest book to movie differences in The Love Hypothesis…