Gwyneth Paltrow and Joely Richardson are set to join Mark Ruffalo and Tim Robbins in Stuart Blumberg’s directorial debut, “Thanks for Sharing,” a co-production of Class 5 Films (“Leaves of Grass”) and Olympus Pictures (“Beginners”).Blumberg, who’s coming off an Oscar nom for co-writing “The Kids Are All Right,” helms from a script he co-wrote with Matt Winston. Dramatic comedy follows a group of unlikely friends brought together through their shared determination to recover from sex addiction as they try to forge meaningful relationships for the first time in their lives. Production starts later this month in Gotham. Paltrow will play Phoebe, a successful businesswoman who falls for Ruffalo’s character, while Richardson will play Katie, the wife of Robbins’ character. Olympus will fully finance the pic. Leslie Urdang, Dean Vanech and Miranda de Pencier will produce for Olympus, while William Migliore and David Koplan will produce for Class 5. Blumberg’s Class 5 partner Edward Norton will exec produce. “I couldn’t imagine actors more perfect than Gwyneth, Mark, Tim and Joely for this film, and I can’t wait to see them bring these characters to life with their unique and formidable talents,” Blumberg said. “Bill, Stuart and I are thrilled to welcome Olympus Pictures aboard ‘Thanks for Sharing,’” added Norton. “Their taste and commitment to making quality independent films make them a fantastic partner.” Paltrow plays Matt Damon’s wife in the Steven Soderbergh-helmed thriller “Contagion,” which Warner Bros. releases Friday. She’s also expected to reprise her role as Pepper Potts, love interest to Robert Downey Jr.’s Tony Stark, in the Shane Black-helmed “Iron Man 3.” Richardson will next be seen in Roland Emmerich’s period pic “Anonymous,” which premieres at the Toronto Film Festival. Thesp, who plays Anita Vanger in David Fincher’s “The Girl With the Dragon Tattoo,” recently wrapped Rodrigo Cortes’ thriller “Red Lights,” which stars Robert De Niro and Sigourney Weaver. Paltrow is repped by UTA and Brillstein Entertainment Partners. ICM and Ken McReddie Associates rep Richardson.