Mischa Barton says she and Ben McKenzie secretly dated during 'The O.C.'

Mischa Barton says her romance with Ben McKenzie during "The O.C." wasn't just onscreen.

The actor, who played high school student Marissa Cooper on the hit 2000s show, told host Alex Cooper on the Feb. 21 episode of the "Call Her Daddy" podcast that she and McKenzie were in a relationship right from the beginning of the filming.

"Yeah it wasn't just on screen either," Barton said. "I mean it was kind of complicated for me. I went into that like a virgin, like a kid, like really feeling like I needed to grow up quickly."

Barton, 38, said she was 17 and McKenzie was 25 when they started dating. He played fellow student Ryan Atwood on the show.

"That was my first (relationship)," she said. "I had no idea what I was doing."

She added that it created tension on the set of the Fox series, which ran for four seasons from 2003 to 2007.

"And I think that kind of set things off on the wrong foot, too, because it was like people hook up on these shows and whatever and these things happen," she said. "But we threw ourselves all into it very fast.

"Notoriously, there was a lot of inter-dating on that show and different people getting together. It definitely was tricky that it happened like right out of the gate. And I felt overwhelmed and not ready for any of that."

Barton said the show's producers went to her parents about the relationship with McKenzie at one point.

"It was kind of a whole ordeal," she said. "That's in the very beginning of the show before we're even halfway through a season, so there was a lot going on there."

TODAY.com reached out to reps for McKenzie for comment.

Barton left the show after the third season. She said she ended the relationship with McKenzie while the two were still acting together on the show.

"We just had to suck it up and get on with it, but there was a lot of like jabs behind the scenes and off camera," Barton said. "I felt like that kind of ostracized me as well because there was a marked difference in maturity level there."

The actor said she felt "not mature enough" to continue the relationship and that it was "overwhelming."

"One of those things you're so young you realize like I'm not ready for this," she said. "I have no idea what I'm doing."

Their offscreen relationship was also reflected on the show.

"There was such great chemistry between the characters, and I think people did fall in love with them because there was genuine friendship and love there on some level," she said.

This article was originally published on TODAY.com