She said: "When I first met him, I had never even met a celebrity in my life before. I was like, 'Oh my gosh Hef,' and then we started talking.
"And we both studied psychology in school. He's very intriguing, I'll ask him a million questions. I'll ask him everything and we'll watch all of his documentaries and he loves revisiting all of that stuff.
"And I love learning about all the history ... Just being more involved in his life and learning about Playboy and all the things he has done to change the world."
Crystal - who is the father-of-four's third wife - says the build up to their first wedding was a "big ordeal".
She said: "Last time it turned into a big ordeal and then it all fell apart."
- BANG! Showbiz