HELP! How do hang-in-the-air endings work?

@TaniaHershman has a terrific story up on PANK Magazine today (thanks @JonPinnock for  the headsup)

I envy writers who can make these 'hang-in-the-air' stories work. If I tried one it would simply appear unfinished. I guess the secret lies in the characterization and believability - the verisimilitude  - in Tania's story, which makes it seem like a slice of real life and therefore acceptable as a snapshot of a moving target? How am I doing?

I want to understand how this works. I need to learn – fast.

All serious advice will be gratefully received and faithfully applied by this apprentice writer.

Although I can't pay, you may help yourself to virtual tea and biscuits.

But, please, do turn the lights off when you leave.

With grateful thanks in anticipation.

Oscar