No one is responsible for your obsession except for you. She made it clear many times that she was annoyed by you stalking her. She shut down her email eventually and her Facebook. I think you’ve read into her overtures of any niceness towards you. It seems clear that she didn’t want to pursue a friendship with you. You ask why she wasn’t interested? You harassed her to the point where she had to shut you off permanently. You need to own up to the fact that you pushed things too far with this person due to an obsession and you’re still obsessed 10 years later. This is a problem and unless you own up to your behavior it’s going to continue.