Segel, the star of TV's "How I Met Your Mother" and the short-lived "Freaks & Geeks," previously worked with Stoller on the soon-to-be-released "Forgetting Sarah Marshall," Variety.com said.
Filmmaker Judd Apatow is a producer on both "Sarah" and "Engagement."
"('Engagement' is) definitely an extension of our desire to explore the depth of human misery," Stoller told the trade newspaper. "If Sarah Marshall (played by Kristen Bell) and Jason's character had stayed together, this might be the sequel."
Stoller and Segel met while working on Apatow's TV series "Undeclared." Segel also had a role in Apatow's "Knocked Up" and Apatow was a writer, director and executive producer on "Freaks & Geeks."