There is an old proverb which states, "revenge is a dish best...." ummm, I should say, "stories are not written, they are rewritten." When you complete your masterpiece, what you have is a first draft and unless you are some kind of genetic anomaly - most people are not - it will not be in a state of publication readiness. It needs to be rewritten. But this rewriting stage can be a terrible trap. It can lead to fiddling, which is a good thing if you are in an orchestra, but a bad thing when you are trying to place the stamp of "finished" on your short story, script or novel.
So what do can one do? Well, there comes a time in every young stories life when it needs to leave home. It needs to get away and see if it can make it on its own, fly from the nest, set sail, and hit the editors slush pile to be scrutinized. Terrifying isn’t it? But an even worse fate for your creation is fiddling with it endlessly, thinking you can improve it, make it better, so good it will win prizes, make you millions, get you on the Tonight Show. The reality is, if you mess with your work forever you will die before anybody else ever sees it, your hard drive will be reformatted by a scrap dealer, and your printed copies used as parrot cage liners.
Here comes the advice. Make it as good as you can - Contradiction Alert! Contradiction Alert! - well not really. What I mean by make it as good as you can is to make it grammatically correct, have no spelling errors and format it the way the editors want. Most publications have guidelines - follow them. The content of the story itself, the flowery words you use, the plot, the characters, the three headed lemur plotting the downfall of time itself, need not be reworked to death. Get those parts to a point where you are happy - Contradiction Alert! Contradiction Alert! - again, not really.
Seven times maximum - that’s my advice. Never rewrite something more than seven times. If you are starting an eight draft chances are you are rearranging and fiddling. Stop it and move on.
So, if you find yourself rearranging sentences, then putting them back again - fiddling - it is time to check your spelling, grammar and format and send it on its way. Remember, practice writing is what a writer needs too. If you spend all your time editing your only story, when are you going to write the next one? Send it out, work on the next one, and don’t sweat it. If an editor likes your story, even if it is not really the story they want, they may give you advice on how to rework it. You can take their advice, or ship it out to another publisher.
Either way your creation is on its way. And you will find, instead of separation anxiety, you will most likely feel relieved and happy to be have finished a piece and be starting something else.