First off, I wish Demi well, hope she gets herself together. That said, she has always been extremely focused on her looks and her body and is a control freak. I can remember reading interviews/articles years ago about the daily, long and punishing workouts she'd put herself through to maintain the body beautiful. Fine, that's her choice, however the simple fact is she's growing older and she can't put off or erase the signs of aging completely.
My personal take is that Ashton's behavior really destroyed her. Here's a woman obsessed with looking as young and hot as possible, and her younger spouse cheats on her with very young hotties. Liz Smith had a good article today on both Demi and Heather Locklear. They are still very beautiful women, but Hollywood isn't kind and doesn't shower the beautiful but non-Meryl Streep type actresses with roles once they pass well into their forties. If you built your career on your looks and you hotness, you often don't have a lot to stand on. Not saying Demi is a bad actress, but she's no Meryl or even a Sandra Bullock. Range is not exactly her strong point. I actually can believe exhaustion, because she hasn't been setting the world on fire with her acting career, and now the other primary thing that got her attention is also gone. She's at a crossroads, will be interesting to see how she handles it. Again, I wish her peace, serenity, and good things.
Smith article: http://www.wowowow.com/liz-smith/liz...right-by-them/