How often do you give up on a project when it’s 75-99% done? Me, very often. There are a number of reasons for this fear of finishing.
Very often, it has to do with fear that the quality isn’t going to be what you want it to be. Other times, you might be afraid of feedback or criticism. Truman Capote, a short story writer said, “Finishing a book is just like you took a child out in the back yard and shot it.”
Interestingly enough, most of these fears don’t show themselves overtly. In fact, most of the times, there will be another excuse that your mind makes as to why you are stopping. I.e. the story is stupid, not interesting any more etc.
So what can you do?
Write. Just keep going. If you can’t, get someone to report to so that you will feel obliged to continue. Once the draft is done, all will be better and you can edit it into oblivion.