Kaia Gerber and Lewis Pullman Heat Up Venice With PDA

Kaia Gerber and Lewis Pullman are serving up major couple goals ... the hot new pair couldn't keep their hands off each other during a romantic night in Italy.

The supermodel and actor were spotted outside Harry's Bar in Venice on Sunday, where they cuddled up, shared smokes, and packed on the PDA like no one was watching. At one point, Lewis even gave Kaia a playful smack on her backside.

The lovebirds were so wrapped up in each other, they seemed to forget the rest of the world existed. After cozying up at the bar, they attempted to hop a water taxi back to their hotel, but we're told they hit a hilarious snag when they realized the boat didn't take Venmo.

Cue the walk of shame (minus the shame) -- the couple had to head right back to Harry's to grab some cash before making their way home.