User blog comment:IamJakuhoRaikoben/Chapter 493: The White Dragneel, Review./@comment-25334245-20160712035302/@comment-7418318-20160712164114

Do we really have to repeat that over and over again?

No Mashima did not mess up. While it is less common for males to take on their wives name upon marriage, it is possible even in reality.

And this story is a fantasy world, so the rules are whatever the author wants them to be.