The model, 20, and the One Direction singer, 21, looked cozy as they soaked up the sun. Jenner showed off her runway-ready body in a bikini, while Styles shielded his shirtless torso under a towel.
Earlier in the week, the Keeping Up With the Kardashians star was spotted dining with the boy-bander in Anguilla. The duo, who were first linked back in 2013, hit up a restaurant together on Tuesday, December 29.
A source tells Us Weekly the exes are "hooking up again" now that Styles — who also dated Jenner pal Taylor Swift — has some time off from 1D. Adds another insider: "Now that he has a little hiatus and is on vacation, this is him trying to win her back, and it appears to be working."
The second source notes that while Styles was the one to call it quits back in 2014, he was drawn back after seeing her in the Victoria's Secret Fashion Show. "All of his friends were saying how hot and amazing she looked," the source tells Us.
In any case, both seem to be enjoying the R&R — and Jenner in particular could use it. In a recent post on her app and website, she revealed that she was recently hospitalized for exhaustion, and that she was making a conscious effort to relax in the new year.
"I guess my resolution would be to chill out more and have the ability to be a little more spontaneous," she shared. "No matter what, 2016 is going to be the best yet. I can feel it!"
Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics, and more delivered straight to your inbox!