Mischa BartonMischa Barton is reportedly dating the director of her new film, Brett Simon.

Thc couple met while making the The Assassination of a High School President last year and a source told the Daily Mail: “This is a major love affair.”

“They became very close right from the start of shooting last summer .. Mischa was pretty insecure about carrying the movie. Brett was the one who helped her get over that by spending hours alone with her helping her develop her character and refine her performance. That’s how they got together.”

The source added that Brett was the first person Mischa called after her DUI arrest in December and they’ve spent nearly every night together for the last few months: “This is the most serious Mischa’s ever been about a guy and he’s the most mature man she’s ever dated. They’re in love and no matter what happens with the movie, this is going to stay serious.”