Most people pick bad security questions. If you have a stalker, she probably knows enough about you to guess your security questions and change your passwords. (Think about it: high school name, mother's maiden, etc. Nowadays people can get most of the answers from ten minutes on Facebook.) That's keeping you from logging in each time.
Find out how to switch your security questions to something secure. Here's a tip: lie.
My first pick for security question is always "What was your first pet's name?" But I've never answer it with the name of any of my pets. Even my best friends and family would have no idea how to answer it, let alone a stalker.