Tyga's Not Back with Blac Chyna After Chance Run-in in NYC

Tyga's soaking up life in the single lane ... and that's why there's ZERO chance he'll get back with his ex, Blac Chyna.

Sources close to the rapper tell TMZ ... Tyga and BC didn't know they were going to the same event over the weekend. The bash was a birthday party for one of Tyga's business partners ... someone Chyna also knows.

Thing is ... Tyga and Chyna never interacted the entire time they were at the Meatpacking District hot spot, Catch NYC. We're told they also never spoke when the after-party moved over to Marquee.

Sources say Tyga wants to keep things with BC exactly how they are now -- with their previous relationship in the rearview mirror.