She wouldn't be gone (Gruvia)
Juvia had has enough of being ignored by Gray. So she left, when she left Gray realized that he loved her. He called everyone they knew, he called Gramps and Erza, they ain't sayin if they seen her. Gray is riding every train with tears in his eyes. He's beaten the tables, walls. If he loved her this much, maybe she wouldnt be gone.
Natsu disappeared a couple days after Juvia.
This book is based off Blake Shelton's She wouldn't be Gone.