Wow, a lot of doom and gloom on these WIPs. Here's one of my really old posts, which is pretty awkward and full of metaphor and simile, but it might shed a little light on your problem:
Abandoning Your Book?
I liken my current WIP to a date. I owe it to her and myself to have a good time and leave with her after the party is over. I chose her for a reason; I was attracted to her; I wanted to hear what she had to say. I wasn't preoccupied with what she might offer. I only wanted to take that small adventure in time with her and appreciate the ride. Oft times a flirt comes along and tries desperately to get my attention, calling out to me with wind songs and coy invites. I'm dancing right now--I can't be bothered to see what's greener on the other side of the mountain.
If I'm too fickle, I'll never enjoy my date all the way through to completion, but instead have an array of disconnected flirtations with something that I end up fantasizing about. The flirtations are cheap time and flashes in a Kodachrome minute. My real date is solid and a very much worthwhile journey. I owe myself the dignity of a having a quality date and seeing it through to the end. Else, I'll hurt her feelings and waste my time.
Do this: try and recapture that mood you had in the moment of conception--when the idea sparked and lit your mind on fire. It sounded pretty good then, didn't it? IT WAS FABULOUS. Unless you were drunk or hopped up on pills. What's really changed? Nothing has changed. You're letting seeds of doubt burst into nasty little buds and begin to take root. You're talking yourself out of it. Asking questions and giving yourself negative answers. You're warming to failure and cooling to success. Or are you making excuses because you believe you're truly blocked? Or are you just lazy right now? Procrastinating? Have you just read a book where the writing, plot and premise totally blew you away, and you're unconsciously comparing yourself to that author?
Get real. Climb down out of that tree (the one you climbed when something spooked you) and plant your feet on solid ground. The story hasn't changed--you have. You've derailed your creative muse, stuck pins in your own voodoo doll. Cease and desist. Unless you truly believe with all your heart that you've made a huge error and this story has no chance because EVERYBODY says so besides you.
Get right back on that baby and give her a whirl around the floor! Don't you know she's waiting for you?