The two-time Grammy Award nominee, 52, was spotted soaking up some sun with Affleck, 48, on Wednesday, the pair lounging on a yacht off the beautiful Amalfi Coast.
Their tip comes days after ringing in her birthday together.
She kept it cute and nautical in a red and white striped tied bandeau bikini top with high-waisted flowy white trousers. J.Lo finished the look with some square gold aviator sunglasses, matching minimal jewelry and a pair of cork wedges, as she carried a small woven straw handbag.
Lopez and Affleck have also been spotted enjoying a romantic lunch in Capri after celebrating her 52nd birthday at the nightclub L'Opéra in St. Tropez with an intimate group of friends. "They are having a beautiful trip," a source told PEOPLE over the weekend. "They celebrated Jen's birthday at a club last night. She looked gorgeous and very happy."
The couple made their rekindled romance Instagram official during the vacation, when she posted a photo of them sharing a passionate kiss on the yacht. Lopez has been wearing her beau's name close to her heart, sporting a gold Foundrae necklace that read "Ben," which was a birthday gift from the Justice League star.
Their romantic yachting trip comes as her ex Alex Rodriguez also posted photos from another boat off St. Tropez, where he's celebrating his own 46th birthday. "He's with family and friends and people he works with," a source told PEOPLE. "He's doing great and celebrating his birthday and Minnesota Timberwolves sale."
Rodriguez, 46, and Lopez called off their engagement in April after four years together. "We have realized we are better as friends and look forward to remaining so," they said in a joint statement to PEOPLE at the time.
RELATED VIDEO: Jennifer Lopez Is 'Very Happy' with Ben Affleck as They Enjoy Her Birthday Weekend in St. Tropez
It's the second time Lopez and Affleck have dated. The pair 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.
"This is not a summer fling. They are planning a future together," a source recently told PEOPLE. "They have serious talks about how they can make it all work. Between their relationship, their kids and jobs, they know it will be tricky to balance it all."