For a theme to work and the story, which will revolve around the theme, it has to contain three things-
What's the reason for this?
If your theme doesn't contain these three essential elements, then you won't be writing a proper short story. It might turn out to be an essay instead.
You can't achieve emotional depth. Readers become engrossed in stories because of the characters in them. They either become the character (sympathize), or read about an interesting person (empathize).
Emotional depth is achieved when readers use their imagination and senses and/or experiences to live the story through the characters.
Your story will be boring. Why? Without conflict, something to stir things up, nothing happens. And a story, in which nothing happens, is one not worth writing about.
Your characters don't lead carefree lives. Well, not in the instance you are writing about them. In that part of their lives they are faced with a problem. They want something and can't get it because of the conflict, which is preventing them to do so.
And it's that conflict and the struggle the characters has to undergo that keeps us readers interested and in suspense. Will the character succeed or won't he? And when is this all going to happen? And how is it all going to happen?
Something that starts has to finish, one way or another.
Once you have created great characters, which the reader will come to care about, and you have placed them in conflict, that conflict at the end of your story has to be resolved. The characters will achieve their goals or they won't.
That doesn't matter.
You can end your story as you please and as it suits your story -- but you have to end it. Ending the story means resolving the conflict.
Does your theme contain character, conflict, resolution?