I hate whenever I read or hear about people who have been cheated on or are worried about it. This is pretty terrible, no?
Is it because you're afraid of feeling betrayed? Or is it just for shock here that you mention it?
Yes. I hate the feeling of being betrayed, it's a bad feeling.
Feeling bad after being betrayed is normal. There is nothing wrong with that, it is fine to feel that way.
What if I cheat on a girl, because I want to hurt her.
If you get betrayed then it's not a good feeling, you know that. So why would you want to hurt someone on purpose? Be kind to others, it's only one life we have to live to be moral and nice to others.