8.60 Ella's Favorite Song

Lu Yizhou's lips were pursed as he stroked the handwriting on the last page. E… It should be Ellie, right? The only one he knew would cherish Ella as deeply as him was only her. His eyes zeroed in on the word 'betray'. He had a hunch that this entry was supposed to be connected to the third clue and it turned out he was right. 

Unfortunately, there was nothing more to the diary that could elaborate why Ellie would use 'betray' of all words. Who could have betrayed Ella? For what reason?