Crystal Harris: Why I Called Off Hugh Hefner Wedding

The runaway bunny is ready to set the record straight.

Less than 24 hours after news broke that she called off her wedding to Hugh Hefner, Playboy Playmate Crystal Harris explained her shocking decision in a Wednesday chat with Ryan Seacrest on his KIIS-FM radio show.

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Dating since January 2009, Harris, 24, and Playboy founder Hefner, 85, got engaged over the Christmas 2010 holiday, and were set to tie the knot this Saturday at the Playboy Mansion before a crowd of 300 guests.

But it wasn't meant to be. "I called it off because I didn't think it was the right thing for me to do," Harris said.

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But the model and singer (her first single debuts next week) shot down reports of a big blowup fight. "It was mutual between Hef and I. There was no fight, we sat down and we talked about it."

Another false report: Rumors that Harris was seeing another man. "No. Not seeing someone else," she said.

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The couple had been full steam ahead with wedding planning; they shared their invites (requesting charitable donations in lieu of gifts) with Us Weekly in April, and the blonde beauty had her dress (Romona Keveza) and shoes (Aruna Seth ballet flats) all picked out. A TV special documenting the happy day was even planned.

Behind the scenes, however, Harris was struggling. "For a while I've been having second thoughts about everything. I haven't really been at peace with myself lately. I didn't think it was really fair to him," she confessed. "It was all happening too fast for me... Was this what I wanted?"

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After a peaceful chat with Hefner, her one-time hubby-to-be "Understood. We both agreed that it wasn't the best idea to get married. He was doing it for me because he thought it was what I wanted."

And Hefner will be just fine, she insisted. "Hef's doing great. Hef's lifestyle isn't the most normal lifestyle," she said of the notorious bachelor. "This isn't the lifestyle for me, multiple girls all around, it's not the lifestyle I wanted."

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She moved out of the Playboy Mansion yesterday, and plans to split her time between Los Angeles and San Diego, where much of her family lives.

"I feel happy and at peace that everything will be OK," she added. And she and her ex-fiance are on excellent terms.

"I respect him more than anything, and we're still going to be really close."