User blog comment:IamJakuhoRaikoben/Chapter 450: Alone in all the World, Review./@comment-3424593-20150831044341/@comment-1776824-20150831044702

It isn't hard to figure out. They don't hate each other. Zeref wants to destroy the world because it rejects him, whereas Mavis never stopped appreciating life and wants to protect the world. It's just a conflict of interest. .-.