Years after dueting on the 2015 tune "I Know What You Did Last Summer," Camila Cabello and Shawn Mendes are back again ... “I had to drink a lot of wine!” Both had been working on the secret ...

Shawn Mendes revealed that the pair began dating on a major holiday, and it hasn't been "that long" since he became official with Camila Cabello PEOPLE ... during a beach date in Miami.

Camila Cabello is seemingly ringing in the new year with a brand-new love interest. Cabello, 27, was spotted packing on the PDA with Henry Junior Chalhoub during a beach getaway in St. Bart's.