User blog comment:IamJakuhoRaikoben/Chapter 414: Drops of Flame, Review./@comment-5288632-20150105185630/@comment-5288632-20150106074734

Why? Well, obviously, Natsu and Gray would continue arguing about who should have destroyed E.N.D. And if they haven't stalled too much time before Zeref appeared to retrieve the book, E.N.D. would have been gone for good, and Natsu should have helped Igneel to beat Acnologia (which may not be necessary). And to add insult to injury, Gray would make some small harsh words to Natsu about "daddy problems," which would make Natsu snap and the argument would get more violent. For some reason, I have a feeling that Natsu would leave Fairy Tail for revenge against both Zeref and Acnologia alone, without saying goodbye.