User blog comment:Omega natsu2/Fairy Tail Zero: Night of Embarking, Review./@comment-24546844-20140915011055/@comment-7418318-20140915082719

We already know that Mavis is going to die while she's still a child, so that would account for the heart-break.

And even if Yury isn't responsible for her death, he's still the one who found her and decided to take her from the island. In all likelyhood Mavis wouldn't have been put into the situation that killed her, if the Treasure Hunter team refused to take her along, so in that way he's a little responsible (in his own mind anyway) no matter how Mavis is going to die.