With their two grown sons out of the house now, Rob Lowe and his wife, Sheryl's relationship has been reignited. 

"The Outsiders" star, who has been married to makeup artist and jewelry designer Sheryl Berkoff for 33 years, admitted his two sons' departure from the family home has directly impacted the couple's relationship.

"I was sad when they left," he said of sons, Matthew, 31 and John, 28. "And I thought this is the end of that relationship with your kids — it's not. It's just the beginning of a new chapter," he expressed on "The Jennifer Hudson Show," which aired on Monday.

ROB LOWE REVEALS THREE SECRETS TO HIS 31-YEAR MARRIAGE

Rob Lowe in a tuxedo smiles as his wife Sheryl in a sparkly dress looks at him lovingly

Rob Lowe and Sheryl Berkoff have been married for 33 years. (Arnold Jerocki/WireImage/Getty Images)

"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,'" he said enthusiastically. 

"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."

Matthew Lowe in a black suit stands next to John Owen Lowe in a black suit next to father Rob Lowe in a blue shirt and fitted suit next to wife Sheryl in a black top and khaki colored skirt on the red carpet for "Unstable"

Rob Lowe and Sheryl Berkoff are the proud parents of two sons, Matthew Edward, 31, and John Owen, 28. (Gregg DeGuire/FilmMagic)

Lowe also reflected on his under-the-radar nuptials to Sheryl, 33 years ago.

"We didn't want anybody to know about it. We didn't want it to be in the papers. So we had it at a friend's house and told people they were coming to a daytime luncheon with a wedding theme. So when they walked in and saw the alter, they didn't go, ‘What the hell,’" he recounted.

"And then we walked down the aisle," Lowe said, adding that people were stunned to learn it was a real wedding.

Rob Lowe sits on a chair and looks at Jennifer Hudson while on her talkshow

Rob Lowe, who initially was upset about becoming an empty nester, told Jennifer Hudson all the benefits to not having kids in his house any longer. (Mitch Haddad/WBTV via Getty Images)

Lowe has been vocal in his adoration for his wife, admitting just last year the three keys to his successful marriage.

"It's all about who you choose.… Sheryl was and is my best friend. So if you marry for anything other than the fact that it's your best friend, you're at a disadvantage from the jump. 'Cause that will sustain when the other stuff ebbs and flows," he explained on "Table for Two," an iHeartPodcast hosted by Bruce Bozzi.

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Rob Lowe sits in a chair wearing a black shirt and gold chain taping his podcast

Rob Lowe previously shared three tips to a successful marriage. (Emma McIntyre/Getty Images for SiriusXM)

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Another key element to his marriage: forgiveness. 

"People say marriage takes work. I'm not sure if it takes work.… But what it does take is forgiveness. And being really cognizant of what hill you're willing to die on," Lowe explained. 

"You definitely have to stay in the room," he added. "And then I think there is a sense maybe on the outside when one looks at a long marriage and goes ‘Oh, it's been — they're blessed.' True. ‘And it’s a perfect marriage.' There's nothing that's perfect."

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"I think the minute things go south for whatever reason it could be… many many many reasons, I think people can go, ‘Oh, I knew it. This, this is bad. This is a mistake. That marriages don't work.' Everybody has those dark periods," he said.

"When they come, and they do, just like a career, everyone has periods where it's not happenin' like you would like it.… Life is like that, it's ebbs and flows.… You just can't bail on the ebbs. ‘Cause eventually it’ll turn around if you're with the right person."

Rob Lowe in a blue suit and tie soft smiles on the carpet wearing a sparkly silver dress

Rob Lowe said "you got to keep the heat," with your partner to make a relationship work, although "that comes and goes." (Amanda Edwards/Getty Images)

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Lowe also said he thinks a marriage needs "heat."

"If you don't have the heat… and that's a chemical thing. That's like I still have it with Sheryl.… You got to keep the heat," he reiterated. "By the way that comes and goes too. There are days, there are times when you're just like, ‘Uhhh,’ and then all of a sudden you're just wild for somebody. It's one of the great human mysteries."