Justin & Selena I Wanna Love Ya, Treat You Right When in Jamaica ...

Justin Bieber and Selena Gomez are answering Bob Marley's eternal question ... yes, this is definitely love.

Justin and Selena's PDA at Jeremy Bieber and Chelsey Rebelo's Jamaican wedding rose to epic levels, as you can tell from these shots of them hanging poolside this week ... after the ceremony.

It wasn't only a tropical makeout session -- JB seemed to be having a blast imitating the Old Spice guy to a tee -- hands on hips, chest out ... and swan dive into the pool.

As we reported ... the young couple has been practically inseparable since arriving for the wedding Monday in the hills of Montego Bay.

Selena and the Biebs are back stateside as of Thursday, but they've gotta look back on the trip fondly.

Aside from their own relationship ... Justin's got a new baby sis on the way, as you can see from Chelsey's belly.

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