In “Bridget Jones: Mad About the Boy,” the neurotic, lovelorn heroine hasn’t just swapped cigarettes for Nicorette. She’s traded the big screen for Peacock, a second-tier streaming service where the franchise’s fourth entry will debut on Feb. 13.

“[People] will watch this one at home,” says Helen Fielding, the author who created Bridget Jones. “If you’re Bridget’s generation, it will be with a bottle of wine and a tub of ice cream. If you’re Gen Z, it will be with lots of minerals, potions and slippers. But it’s a good movie to watch on the sofa.”

Relegating “Mad About the Boy” to streaming signals how far the romantic comedy has fallen in the 24 years since Bridget first captured audiences’ hearts. When “Bridget Jones’s Diary” hit theaters in 2001, the genre was at its zenith, with Julia Roberts, Reese Witherspoon, Sandra Bullock and of course Bridget herself,...