Selena was seen hanging all over The Weeknd Tuesday night outside Giorgio Baldi in Santa Monica -- getting handsy and mouthy with the singer. We don't know how long this has been going on, but they're definitely a thing ... based on these pics.
There's potential drama here -- Selena's pals with Gigi Hadid ... so her sister, Bella, might have a thing or 2 to say about the hookup.
But as they say, the heart wants what it wants. Same goes for Selena's hands.