Katie Couric is opening up about the sexual harassment allegations against her former “Today” co-host Matt Lauer.

The renowned journalist is getting ready to release her tell-all new book Going There, which will break down some of her most memorable interviews and the biggest moments in her life.

“We have no relationship,” she said in an interview with “Today”, when talking about Lauer, whom she also references in the memoir. The disgraced host was fired by NBC in November 2017 following multiple sexual harassment allegations.

Talking about the revelation of Lauer’s alleged misconduct, Couric said, “As I got more information and learned what was going on behind the scenes, it was really upsetting and disturbing. It was really devastating, but also disgusting.

“I think what I realized is that there was a side of Matt I never really knew,” she continued, “and I tried to understand why he behaved the way he did, and why he was so reckless and callous, and honestly abusive to other women.”

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Couric also spoke to People about Lauer last week, saying, “What upset me the most about hearing these stories [was] that obviously [his behaviour] was grossly inappropriate, but also it just seemed so callous,” Couric told the magazine.

“And that’s not the Matt I knew,” she added. “There’s a duality in human beings, and sometimes they don’t let you see both sides.”

“I think we’ve learned a lot,” Couric shared of the differences that have occurred since she first entered the newsroom.

“I think our understanding of what is a consensual relationship has changed dramatically, and now we know if there is a power dynamic, it can’t really be considered consensual.”

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Insisting she didn’t notice anything alarming about Lauer, Couric said: “He might comment on a movie star or something, saying, like, ‘Oof, she’s unbelievable.’ He was admiring of beautiful women. But I never felt he was pervy or inappropriate in my presence, ever.”

Couric said that she knew Lauer was a “player” but insisted they didn’t discuss “intimate” details regarding their personal lives.

“I think we have all these euphemisms that we used to use for bad behaviour — and ‘player’ was one of them,” she told the mag. “He was a flirt. Certainly I read that he was unhappy in his marriage. But, honestly, I never had that discussion with him.

“I think it’s hard for people to understand that we didn’t share intimate parts of our lives with each other. I could count on one hand the times that I talked to him as I would a confidant or a really close friend.”

She said: “Our offices were next to each other, and so I think when he engaged in this kind of behaviour, he was extraordinarily secretive about it.

“I [had] heard a few pieces of gossip, that he was involved with an anchor, and I remember thinking, Who knows if this is true? I think it was considered nobody’s business. At many news organizations in the ’90s and early 2000s there was a lot of inappropriate fraternization.

“It took me a very, very long time to kind of come to terms with it,” Couric said of the allegations. “Also, to appreciate the damage that was done to women who were taken advantage by many powerful men.”

In her much-talked-about book, Couric wrote about a producer who once called her about an email Lauer sent to her by mistake back in 2004 that mentioned spreading butter on her thighs, among other sexual comments.

“I remember being shocked and disappointed,” she said. “But also I think I thought more about the infidelity aspect than the idea that he was taking advantage of someone. The idea of something being consensual was interpreted very differently than it is now. If I had to do it again, I would have made sure that young woman was okay.”