Why sure! I think everyone does at one time or another. But, here is the good news. Once it is done, put it away for a while and when you see it next you will think, " Hey this is nice, what was the problem?" It was you just got tired of working on it, that is all.
Like some on here, I sometimes put it aside and do a cutsie quick project for a day or so and then go back at it to the end. It really helps!