Sophia Bush is "not allowed" to talk about Chad Michael Murray anymore.

Sophia Bush and Chad Michael Murray

Sophia Bush and Chad Michael Murray

The former 'One Tree Hill' co-stars were briefly wed in 2005 and Sophia - who recently got engaged to Grant Hughes - says she was just a "naive 21-year-old kid" when they tied the knot and Chad is now someone that she doesn't know anymore.

Speaking on Michael Rosenbaum's 'Inside of You' podcast, Sophia, 39, explained: "Oh, I'm not going to talk about him. I'm not allowed to because I've tried to poke fun at being a dumb kid and whenever I've done that, it gets twisted into I'm talking s*** about somebody who I don't even know anymore, who's clearly a grown-up.

"I think you have to laugh at who you used to be, but when people ask me about history that involves someone else…it's not worth my time. It's not a place where I have ill will or anything.

"I've tried to like, you know, do the thing where when I get stuck live on the air—which has happened to me twice - getting asked about it where I give a jazz hands quip and move on. It just doesn't work, so I'm not going to."

Sophia went on to explain that she doesn't believe she was mature enough to be married when she was 21.

She said: "I was a very naïve 21-year-old kid, and that's all there is to it. I think lots of people do stupid s*** before their prefrontal cortexes are fully formed and they're not until they're 26. So you do the math on my timeline. I literally didn't have a whole brain."

And Sophia believes people need to be happy and fulfilled alone before they are ready to wed.

She said: "I think it depends on what people's motivations are and I want to make sure, whether it's myself or one of my best friends, that we're clear on what it is we're signing up for rather than thinking we're getting some Kate Hudson and Matt McConaughey rom-com life. This notion that you're going to meet your person and they're going to make you so happy that you're going to be fulfilled and you'll never be nervous again and you'll never ever think anyone else is hot - like what? It's such an absurd joke."