EXCLUSIVE

"Bachelor in Paradise" stars Izzy Goodkind and Vinny Ventiera are making the quantum leap from epic TV breakup to real-life PDA ... at 30,000 feet.

We got a pic of Izzy and Vinny getting cozy Wednesday during their L.A. to NYC flight, and they didn't seem too concerned with any spoiler alerts. Passengers say they couldn't keep their hands off each other ... and Izzy eventually fell asleep in his lap.

Worth noting: Vinny took a center seat to sit next to her. THAT's gotta be love.

As of Tuesday night's 'BiP' this seemed totally improbable -- Vinny left the island after a blowout fight with Izzy. So, what changed between taping the show and now?

Our photog got them at LAX right before they boarded the flight. They tried peddling that ole "just friends" bit ... until Izzy blew their cover. Check it out.