Realism
A man and a woman drink beers while waiting for a train to arrive. They bicker passive aggressively. The end.
Yep—that sounds pretty realistic to us. One of the strengths—perhaps the key strength—of Hemingway's writing is his adherence to remaining realistic. His characters are often bitter, nasty, and disenchanted. His love stories don't end with a bang, but with a whimper. His settings, although beautiful, are often depicted as shabby.
What Hemingway is giving the reader is a reflection of the world we inhabit: cruel, opaque, and utterly mysterious despite seeming straightforward.