I'm sorry about your ordeal. Love is complicated indeed. :(    I think that there are definitely  some  people who will try to change their significant others. I have come across men who thought they were entitled to try to change me.     Some people think that if they have an intense physical attraction for someone, then that makes it okay to try to change that person.     Perhaps your ex genuinely thought that your views were okay because she didn't know what she was getting into. After knowing you for awhile and learning more about it, she probably realized that it wasn't for her.     However, giving anyone an ultimatum is a 'no no' for sure. If there's a 'deal breaker', then leave. Unfortunately, some people aren't mature enough to do this.