Because messing with stuff, for good or bad, takes away the freewill aspect. It really might be that simple. Although I know it's unfair. I like to believe we can change things to 'good' on our own a lot of the time.
I don't wanna pry about the bad stuff in your life, but I'm sorry nonetheless.
[ooc: The Buffyverse rocks, yea?! I love it. It was my first main fandom.]