Hugh Hefner and Crystal Harris. (Dan Kitwood/GETTY IMAGES)

“The wedding is off,” Hefner tweeted on Tuesday. “Crystal has had a change of heart.”

“After much deep reflection and thought I have decided to end my engagement,” Harris said in a statement posted to her Web site. “I have the utmost respect for Hef and wish him the best going forward. I hope the media will give each of us the privacy we deserve during this time.”

More than 300 people were invited to the wedding of the “Playboy” mogul and his much younger playmate set for this Saturday, June 18. The couple’s nuptials were set to air on Lifetime this July in the two-hour special, “Marrying Hef.”

Citing multiple sources at the Playboy mansion, TMZ reported Tuesday that the couple had an argument on the phone and that Harris had moved out.

Harris’s manager, Michael Blake ,confirmed the news to People, adding, “The split was a mutual decision, and the two remain good friends.”

Harris may have hinted at the breakup when she tweeted this quote attributed to Buddha on Monday: “There are two mistakes one can make along the road to truth...not going all the way, and not starting.”

In a move that now seems rather odd, Harris promoted a Funny or Die video parodying the couple’s relationship on Twitter on Tuesday.

This would have been the third marriage for Hefner, 85, and the first for Harris, 25.