Sources close to the former couple tell TMZ ... the "Ghost Adventures" star and former Playboy model called it quits a few weeks ago. It's unclear what led to the split after nearly 2 years of dating ... but we're told there's no bad blood between them, no pun intended.
In fact ... our sources say they remain friends and are still on talking terms.
TMZ broke the story ... Holly went to Zak's Haunted Museum in Las Vegas back in May 2019 and sparks started flying. It wasn't long before they started dating. They had kept the relationship on the down-low but their cover was blown thanks to some hawk-eyed fans who picked up similarities on their Instagram stories ... sparking questions as to whether they're an item or not.
Along the way, it seemed some of Zak's paranormal interests rubbed off on her ... like when she and Bridget Marquardt reunited for a séance to reconnect with a famous ex.
Holly, of course, famously dated Hugh Hefner. She would go on to marry Pasquale Rotella in 2013, but Pasquale filed for divorce in September 2018.