Writing A Short Story - Like a Virgin

I'm trying to put together a decent 3,000-5,000 word piece to submit to New Asian Writing.  It is about a Bangkok cop who has a girlfriend addicted to meth that he loves and the problems that ensue. My Thai colleagues have informed me that writing about her stabbing him would be too cliche, so I put in an different kind of ending that I thought might be interesting.

The problem I'm having is that there's too much setting up the narrative through the initial action and conflict, and then it just ends rather quickly.  So, it's kind of like getting laid for the first time - all the build up and excitement, and then two seconds later the whole thing is over.

If it was a novella (~20K words), it would be no problem, since you always have some space to throw in some new characters, more dialogue, different situations, or more backstory.   Flash fiction (<1,000 words) is also easier, in my opinion, because you only have to explain one moment in time followed by a zinger at the end. For short stories the reader, at least when I'm reading, wants a little bit of plot development, more than just a one or two interesting characters, well-explained conflict, and a good ending.  It's hard to do in under 5,000 words.

Hopefully this story will come together by the second edit.  Guidance is much appreciated.

Writing A Short Story - Like a Virgin