Mark Ruffalo said he's not friends with Jennifer Garner because of her husband Ben Affleck. Credit: Jim Spellman/WireImage; Jason LaVeris/FilmMagic; David Becker/Getty Images

Not Matty! They may have played best friends-turned-lovers in the beloved 2004 romantic comedy 13 Going on 30, but Mark Ruffalo and Jennifer Garner are no longer friends for one big reason—Ben Affleck

On Thursday, June 26, the Begin Again actor, 46, appeared on Watch What Happens Live with his costar Keira Knightley. When a fan called in to ask if Ruffalo kept in touch with Garner, he shook his head. 

"We had a great time together, and I think we would, but then Ben [Affleck] came on the scene and that was the end of that," Ruffalo said smiling. 

"I heard he doesn't allow her to have male friends," host Andy Cohen said, joking, "I made that up!"

Ruffalo shrugged and pled the fifth, adding that it was "sad" he hadn't stayed close with the Alias star in the 10 years since the film was released. 

The same year 13 Going on 30 was released, Garner started dating Affleck and the pair married in June 2005. They have three children together—daughters Violet, 8, and Seraphina, 5, and son Samuel, 2.

Ruffalo has been married to French-American actress Sunrise Coigney since 2000, and they have three children together.