"They are back in L.A. now after the most special trip to Europe," a source tells PEOPLE. "They are hanging out with their kids and friends. They are having an amazing summer."
Affleck, 48, and Lopez, 52, are currently focused on bonding before getting back to work, the source says.
"They are spending as much time together as possible before they have separate work projects in the fall," adds the source. "Ben will be filming in Texas and Jennifer in Canada."
Over the weekend, the couple was spotted together taking a beachside stroll with Affleck's best friend Matt Damon.
Alexander Tamargo/Getty Images; Paras Griffin/Getty Images for Warner Bros. Jennifer Lopez, Ben Affleck
Walking in Malibu, near Paradise Cove, Affleck and Lopez held hands as Damon, 50, walked alongside the pair.
Late last month, while chatting with Extra at the premiere of his latest film Stillwater in New York City, Damon talked about Affleck and his rekindled romance with Lopez, telling the outlet, "I'm just so happy for him."
"He's the best. He deserves every happiness in the world," the actor added of his longtime friend. "I'm glad for both of them."
RELATED VIDEO: Jennifer Lopez Is 'Very Happy' with Ben Affleck as They Enjoy Her Birthday Weekend in St. Tropez
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The couple made their rekindled romance Instagram official during their European vacation, when Lopez posted a photo of the couple sharing a passionate kiss on a yacht.
The couple originally began dating in July 2002 after filming Gigli together. They got engaged that November before postponing their September 2003 wedding, just days before the date, and ultimately calling off their engagement in January 2004.
A source recently told PEOPLE that the pair "are madly in love" and "the loves of each other's lives."