Kristin Cavallari and Boyfriend Pose with ‘Laguna Beach’ Castmates in Nashville

Kristin Cavallari‘s boyfriend Mark Estes is officially part of the Laguna Beach crew!

Estes, 24, and Cavallari, 37, posed with a group of Laguna Beach alums and their significant others in Nashville, where the Uncommon James founder lives, as seen in an Instagram post shared by former castmate Jason Wahler on Saturday, May 4.

“Nashville takeover! 🙌🙌,” Wahler, 36, captioned the post. He tagged costar Talan Torriero, who was absent from the photo, asking him, “Where you at?”

A number of alums of the MTV hit were present at the gathering with Wahler, Cavallari and their partners — including Alex Murrel, Jessica Smith Evans and Lauren “Lala” Olsen.

The nostalgic Laguna Beach hangout comes after a source told PEOPLE that Cavallari and Estes are enjoying their budding romance.

“Everything is so good with Mark and he’s great with her kids. They have a lot of fun together. It’s honestly the happiest her friends have seen her in the past 10 years,” the insider said of The Hills alum.

Cavallari shares three kids with ex-husband Jay Cutler — Camden, 11, Jaxon, 9, and Saylor, 8 — whom the source said remain the top “priority” in her life.

“They are No. 1 no matter what. She will pass on projects because she wants to be with them and she doesn’t have nannies 24/7,” the source said, adding, “She has a very tight group of girlfriends and they have mom time. She purposefully keeps her circle very small now.”

The source said the Very Cavallari star is in a “fun phase” of life after she “got married so young and had kids so young.”

“She’s learning to enjoy the moment,” they added of the TV star, who hard-launched her relationship with Estes on Instagram in February.