Deadline reports that Showtime has canceled Masters of Sex, Michelle Ashford’s decades-spanning historical drama series about sex research pioneers William Masters (Michael Sheen) and Virginia Johnson (Lizzy Caplan). Its fourth and final season, which ended with the two characters getting married, concluded earlier this month.

The decision is something of a departure for Showtime. Over the years, the network has developed a reputation for leaving its signature series, such as Weeds and Dexter, on the air long past their expiration dates. With Masters of Sex, however, the show suffered from ratings declines in addition to—after a promising first season that was met with modest awards recognition—significant drops in quality.

While Sheen and Caplan (who received an Emmy nomination for her performance) continued to do strong work on the show even as it lost all traceable buzz, Ashford simply couldn’t keep up with the pressures of an extended timeline. Her first season was relatively tight, smartly exploring the budding partnership between Masters and Johnson while spotlighting supporting characters played by the likes of Beau Bridges, Nicholas D’Agosto, and the great Allison Janney. Unfortunately, Ashford—who initially wanted to take the story from the ’50s through to the ’80s—apparently felt the need to start moving at a faster clip.

By Season 2, Masters had become reliant on abrupt time-jumps with too much filler in between. The series’ storytelling grew increasingly scattered, and in turn, it lost its grip on its characters, holding onto some past their relevance and throwing others into exceedingly bizarre situations. (Its “jump the shark” moment arguably came in the Season 3 episode “Monkey Business,” in which Johnson attempted to sexually arouse a gorilla for the entire installment—as the A.V. Club’s John Teti put it, it was “as bad as it sounds.”) Thus while the show was still capable of producing strong individual episodes, like Season 4’s “Coats or Keys,” Masters’ diminished overall stature likely rendered cancellation an unfortunately easy choice for Showtime.