(Image from Hyperbole and a Half)
Is it because I don't want to tell them? Nope. They're nothing but supportive. They pretty much need a medal to put up with me vanishing to write the first draft. And the second draft. And revisions.
It doesn't mean I don't love them. It doesn't mean I'm not dying to share my latest crazy brain activities with them. But I allow myself to be a bit of a selfish shellfish. I write that first draft for me.
ME! ME! ME!
We've heard thousands of times to write the story you want to read. It's true. If you don't want to read about your character or love them or want to torture them into submission with a plot twist of evil (yeah, I'm that kind of writer) then who else will care?
Sure it won't be perfect. They'll be loads you can improve on and change. You may even (whispers) shelve the manuscript.
I love getting feedback that kicks my butt into gear. That makes me focus on the bits I've edged away from. But, until that moment arrives, I give you permission to be selfish. Make the mistakes you need to grow as a storyteller. Be indulgent. Throw in a dinosaur who eats the villain (you'll delete it before your CP's see... Okay, maybe don't add a dinosaur if your story isn't set then. hee hee).
Hug your first draft close while you can. Like a small child it will change and grow. It won't want you to hug it forever. *sniff* It will become a grumpy second/third draft teenager (and make you hack it to editing pieces), but the love will still be there. Why? Because it was a labour of love in the beginning.
Then your job is to help it grow and make others love it.