Rob Lowe had crush on Demi Moore, said hook-ups were ‘inevitable’ on ‘St. Elmo’s Fire’ set

Rob Lowe is remembering the wilder days of the Brat Pack while filming "St. Elmo’s Fire."

While appearing on "SiriusXM’s ‘Let’s Talk Off Camera with Kelly Ripa,’" Lowe joked that the set was a "big sex orgy."

He said he had a crush on Demi Moore and they "briefly had a thing" before she and Emilio Estevez were engaged.

"Anytime you put young 20-something men and women together, hookups are inevitable. I don’t think that has changed," the "Parks and Recreation" star said.

ROB LOWE RECALLS FILMING HIS 'ABOUT LAST NIGHT' SEX SCENES WITH DEMI MOORE: IT’S 'VERY BORING'

But then, just as quickly, relationships changed and Moore was married to Bruce Willis.

Lowe recalled, "And then we all were at her wedding to Bruce. Biggest wedding I’d been to up until then. I had never been to a wedding like that. There were, I think, two sound stages rented, and bands and so fun, and amazing."

Lowe, meanwhile, has been married to his wife Sheryl Berkoff for 33 years, after initially being set up on a blind date, or as he joked a "half-blind" date since he was a movie star at that point.

Initially, the timing didn’t quite work, but they met again on the set of a movie where she was working as a make-up artist and things rekindled.

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He took her on a press tour with him and stopped in Fiji on the way home, and that’s when he had an "epiphany."

Lowe saw their names on a hotel door "and I was overwhelmed with a sense that we were going to be together, that we were going to have children, all of this stuff. And that could not have been farther from where my head was, farther from my ability to even deliver on. And that is what indeed happened. And, that was the beginning of us dating."

The couple married in 1991 and share two sons, Matthew and John Owen.

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Last month, Lowe talked about becoming an empty-nester and reigniting the spark with his wife during an appearance on "The Jennifer Hudson Show."

"Becoming [an empty-nester] was actually super emotional for me," he said. "I was so sad. And then once they were out of the house, I looked at my wife and went, ‘Wait a minute, I remember you! You’re hot! And we have fun together.'"

"And all of a sudden, I could wake up in the middle of the night and go get a midnight snack without any clothes on again. It was very freeing. I love being an empty-nester now."

New episodes of SiriusXM's "Let's Talk Off Camera with Kelly Ripa" are available every Wednesday on the SiriusXM app and wherever podcasts are available.