Jennifer Aniston Looking Super Sad Post Justin Theroux Split

Jennifer Aniston made a rare public outing since announcing her split from Justin Theroux ... and she did not look happy.

Jen was spotted leaving Grauman's Chinese Theater Wednesday night after the premiere of her longtime friend Jason Bateman's new movie, "Game Night." She and Jason have been close for nearly 20 years and have done 5 movies together.

However, 'Game' is an action comedy ... so it seems unlikely that is the reason for her solemn face.

As we reported ... Aniston and Theroux announced their separation last week and all signs point to divorce being the next step. We did some digging, though, and they might not ever have been legally married -- which would certainly make the split go smoother, for the lawyers, anyway.