At the Wednesday premiere for “Sleeping with Other People” at the ArcLight Hollywood, Alison Brie said the darkness was what drew her to Leslye Headland‘s romantic comedy.

“I love that the movie is a romantic comedy but it has a lot of depth to it and a lot of darker moments,” Brie said. “You see the characters alone a lot. Leslye was able to shift seamlessly from a dramatic tone to a comedic tone, even in the same scene.”

The movie follows Brie and Jason Sudeikis‘ characters, serial cheaters who can’t hold down a relationship, who meet 12 years after a one-night stand. Despite a mutual attraction, the two vow to remain just friends and help each other with their monogamy issues.

Brie said “Sleeping with Other People” felt like a more modern romantic comedy.

“I think it has a lot to do with the very candid dialogue,” Brie said. “These characters are so frank in the way that they talk about sex and relationships and especially having people of the opposite sex having those conversations together is a very current thing. I think people are very open about sex and they’re having a lot of it today in their dating lives.”

“I think two of the most relative things are romance and comedy,” Sudeikis said. “I’m really proud of the tone and the world that Leslye created, both on the page and then executed wonderfully on screen.”

Despite the heat, the film’s stars and premiere guests made their way over to the after-party at Wood & Vine for Dark Horse wine, cocktails and canapes. Brie was there with fiance Dave Franco, Lizzy Caplan made an appearance, and “The League” co-stars Nick Kroll and Katie Aselton came out to support Jason Mantzoukas.

IFC’s “Sleeping with Other People” also stars Amanda Peet, Adam Scott, Andrea Savage, Natasha Lyonne and Adam Brody and opens in theaters Friday, Sept. 11.

(Pictured: Leslye Headland, Dave Franco and Alison Brie at the “Sleeping With Other People” after-party)