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What fun is romance without a little PDA?

Longtime lovebirds Demi Lovato and Wilmer Valderrama have been swimming -- and kissing -- in the tropical climes of St. Barts this week, sharing photos of one another taking dips in the Caribbean waters while snuggling up against one another.

People even spotted the pair showing off their "Dirty Dancing" skills as Demi, 23, jumped into the arms of her 35-year-old beau a la Jennifer Gray and Patrick Swayze's famous "lift" scene.

"I am very, very in love with him," Demi said on a New Zealand radio station this past summer. "I think we'll probably wait a little bit longer, but if he asked tomorrow, I'd say yes."

Wilmer and Demi's relationship has weathered some tough times. While he's stuck by his partner as she battled addictions and an eating disorder, he's also continued to push her to be the best she can be.

"I am proud and honored to be front row to see the world you are about to change," he wrote on Instagram in March on the third anniversary of her sobriety. "I love you Demi."