Hugh Hefner's fiancee Crystal Harris is a real-life runaway bride -- 5 days before walking down the aisle ... she bailed out of the Playboy Mansion and multiple sources say the wedding is off!
Our sources -- who are all at the mansion -- say Crystal and Hef had a nasty argument this weekend on the phone. When the dust settled Crystal decided to 86 the nuptials and quickly moved her stuff out.
The wedding was supposed to go down Saturday.
This would have been Hef's, umm ... third marriage.