LOS ANGELES (Reuters) - Heartbroken Playboy founder Hugh Hefner said on Tuesday his wedding this weekend was canceled because his 25-year-old fiancee, a Playmate from his magazine, changed her mind. Hefner, 85, and Crystal Harris were due to tie the knot in front of more than 300 guests at the Playboy Mansion in Los Angeles on Saturday. It would have been Hefners third marriage. The wedding is off. Crystal has had a change of heart, Hefner wrote on Twitter. The breakup is a heart breaker, but better now than after the marriage, he added later. He also denied a report on celebrity website TMZ.com that the couple had had a nasty argument on the phone. Adding insult to injury, he said Harris took his favorite pet, a cocker spaniel named Charlie, when she moved out of the mansion. On the other hand, Hefner said he has been consoled by his coterie of old pals and his former wife Kimberley Conrad, and announced he would be hosting a screening of Runaway Bride. Hefner proposed to Harris on Christmas Eve, he announced on Twitter at the time. Since then Hefner has been planning the nuptials in between serving as hands-on editor of Playboy and entertaining family and friends at movie screenings and backgammon games. A two-hour TV special featuring wedding highlights was due to air July 13 on the womens cable channel Lifetime.