The actress and the country music star tied the knot in Sydney in 2006 and share daughters Sunday and Faith

Nicole Kidman and Keith Urban. PHOTO: NICOLE KIDMAN/INSTAGRAM

Nicole Kidman is celebrating her “forever” love with husband Keith Urban.

On Tuesday, June 25, the actress, 57, marked the couple’s 18th wedding anniversary by sharing a romantic photo of the pair. In the intimate shot, Kidman is barefoot and wearing a colorful patterned dress as she lies on a stone wall in front of a sweeping view of the sea.

The country music star, 57, is sitting on the wall by her head, strumming an acoustic guitar. He is also barefoot and dressed in a bright pink shirt and black pants.

Kidman captioned the post simply, “Forever ❤️,” adding the hashtag “happyanniversary.”

Nicole Kidman and Keith Urban.NICOLE KIDMAN/INSTAGRAM

A number of the pair’s celebrity friends left their well-wishes in the comments, including Naomi Watts, who wrote, “This looks like true love ❤️🙌❤️ heavenly 🙌❤️.”

Rita Wilson commented, “Love you both. Happy Anniversary, lovers. ❤️.”

Kidman and Urban, who first met at the G’Day USA gala in 2005, tied the knot the following year in a candlelit ceremony at St. Patrick’s Estate in the Sydney beachside suburb of Manly, Australia. The pair welcomed their first child together, daughter Sunday Rose, in July 2008, followed by daughter  Faith Margaret in December 2010.

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The couple faced a difficult period early on in their marriage when Urban was struggling with addiction.

Nicole Kidman and Keith Urban attend the 2023 CMA Awards.TAYLOR HILL/WIREIMAGE

Urban addressed that difficult time earlier this year when he gave a touching speech in honor of his wife at the 49th AFI Life Achievement Award Gala. He credited Kidman for always loving and supporting him, particularly amid his addiction recovery.

“We got married in June 2006 and barely four months into our marriage, my addictions … that I’d done really nothing about, blew our marriage to smithereens,” the “Straight Line” singer said in his speech at the gala in April, per a video of the event posted on June 18.

“Four months into a marriage, I’m in rehab for three months. I had no idea what was going to happen to us … and if you want to see what love in action really looks like, give that a whirl,” Urban continued. “Nic pushed through every negative voice, I’m sure even some of her own and she chose love. And here we are tonight, 18 years later.”

Keith Urban and Nicole Kidman attend the 49th AFI Life Achievement Award Gala Tribute on April 27, 2024.AXELLE/BAUER-GRIFFIN/FILMMAGIC

Kidman opened up about her love for Urban in an interview for PEOPLE’s 50th anniversary special issue in April.

“I’m so lucky that I have Keith who’s just my love, my deep, deep love,” said the Oscar winner, who previously spoke to PEOPLE about how quickly she fell for her husband.

“It was my [38th] birthday, and he stood outside with gardenias at 5 a.m. on my stoop in New York,” Kidman shared in 2019. “That is when I went, ‘This is the man I hope I get to marry.’ “

“I believed by that point he was the love of my life,” she said. “Maybe that’s because I am deeply romantic, or I’m an actress, or I have strong faith as well, but I just believed, ‘Oh, okay, here he is.’ “

In a surprise to fans, Urban recently debuted clips from the couple’s wedding during a concert in Las Vegas in March 2023, as he sang his hit “Without You.”

“I wanted to do it in a very organic way and find the right song,” he told PEOPLE of his decision to share the previously private footage. “It was really more about choosing to do that song, ‘Without You,’ and how that felt like the right time for that.”