i have several pieces in various stages of completion. A couple of unfinished novels along with several articles that need tuning. I don't feel guilty and I intend to finish what I've started but I'm sure I will always have some things that I never completely finish. I also expect that when I finish my "novels" they will probably look a lot different than when I started them. To me writing, like ideas and thought, evolves constantly. I think writing is an ongoing journey with lots of twists and turns along the way that help us learn and grow as writers. I have no doubt that my portfolio will always contain "unfinished" pieces and to me that's just fine. I would be much more concerned if I every found my portfolio empty. Don't worry if you haven't finished your book yet...set it aside and try something else for awhile. The important thing is to just keep writing and eventually you'll get there.