Ben Affleck, Jennifer Garner, and her ever-expanding bump were spied arriving in LAX . . . and looking completely frazzled even after a nice weekend in Florida (where they were seen hanging out with Matt Damon and heavily pregnant Luciana Barroso).

Things got even more heated as the couple left the LAX terminal and reached the outdoors-- Ben protected Jennifer by pushing photographers out of the way as they got too close for comfort.