Trying to find a reason why someone doesn't like you can be counterproductive.

Everyone has reasons for not liking someone. Maybe their reasons are valid and you're a jerk, or maybe they're because the person is an egoistic jerk, but maybe its just because some people don't vibe, and that's OK.

End of the day its what you think of you. If you can confidently say that you've been the best person you can be and someone still didn't like you, its nothing to mull over.