Adam Brody had his girlfriend, Leighton Meester, by his side to celebrate the premiere of his film Some Girl(s) in LA last night. He also linked up with his costars Jennifer Morrison and Mia Maestro on the red carpet to debut the film ahead of its release in NYC and LA on Friday. While he walked the carpet with Jennifer and Mia, it was Leighton who had his arm as they left the afterparty later that evening, marking their first public event together as a couple. The pair began dating back in February and have been sneaking in dates together around LA ever since. Most recently, Leighton showed skin for a breakfast date with Adam over the weekend. They will also be hitting the big screen together soon since they are currently working on their latest collaboration, Life Partners, which is due out in 2014.