Justin Bieber and Hailey Baldwin Kissing in a Brooklyn Park

Justin Bieber and Hailey Baldwin reunion is now complete after an intense make out session in a Brooklyn park ... which looks like it's straight out of a Nicholas Sparks movie.

Biebs and the Baldwin were overlooking the NYC's East River on Saturday while their lips got totally reacquainted up against a railing. After the PDA in BK's Domino Park they didn't exactly come up for air. They crossed the river into lower Manhattan in the evening, and kissed some more in Rockefeller Park.

All this romance tops off more than a week of non-stop contact between the former exes.

The couple spent all last weekend together in Miami, before jetting off to NYC ... where Justin's been in a ridiculously great mood.