I feel for this guy. I’ve been there.
This is the third time it has happened to me, and it prompted me to think about the reasons why it happens. Lack of motivation, a poor idea, weak characters or simply a lousy plot are probably common elements, but these can usually be fixed in one way or another. What I believe happened is that I just didn’t attach myself to the main characters and failed to have an underlying message I wanted to get across. With this most recent admission of failure, I have to say that I completely lost my way, and although thinking I was following my plot outline, I was in actual fact wandering off in all directions.