Sophia Bush shares why she won't talk about her ex Chad Michael Murray

Sophia Bush has never been cagey during interviews, but there is one topic she'd rather avoid: her ex-husband, Chad Michael Murray.

The former "One Tree Hill" stars were briefly married from 2005 until 2006. In the past, Bush, 39, has joked about their short-lived union, which took place when each was in their early 20s.

But when she was asked recently about Murray during an appearance on the "Inside of You" podcast, she refused to discuss him.

"Oh, I'm not going to talk about him," Bush told host Michael Rosenbaum. "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, like, laugh at who you used to be," she continued. "But when people ask me about history that involves someone else ... it's not worth my time. It's not a place where I harbor ill will or anything."

Being young, explained the "False Positive" star, had everything to do with her and Murray's rush to the altar — and their split after just five months of matrimony.

"I was a very naïve 21-year-old kid," she said, "and that's all there is to it."

She later added, "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."

Though she's reticent to talk about her relationship with Murray, Bush has nothing but love for former "OTH" co-stars Bethany Joy Lenz and Hilarie Burton, with whom she hosts a new podcast called "Drama Queens."

Lenz and Burton brought Bush to tears during her visit last month to TODAY when they sent in sweet video messages in honor of her 39th birthday.

“Happy birthday, Sophia! I love you so much. I love our friendship. I’m so grateful for you,” Lenz said in her message. “Thank you for your openness and your big, giant, compassionate, loving heart.”

Meanwhile, Burton gushed, “I love you. You have been a tireless advocate for so many people, me included. And you’ve defended me and included me and I just love you so so much.”

A visibly choked-up Bush responded, "Well, I wasn’t prepared for that. Thank you so much.”