As she looked out the window, reminscing the times with Lee Donghae, and the day supposed which was supposed to be marked as their  1000th day, was all too heartbreaking for her, they broke up leaving her in a devastated situation. 

Why did he broke up with her? 

No one knows why.

Not even the girlfriend, scratch that, ex - Girlfriend, Jung Jessica, knows why.

Memories of him kept replaying in her mind, making her devastated again.