Loss

Loss is a hard thing that everypony has to get over in their life-time. When Twilight ends up in the hospital, Rainbow blames herself,never leaving Twilight's side for a moment.

Rainbow Dash has had feelings for Twilight for a long time. She was going to tell Twilight how she felt, when an accident landed them both in hospital. Rainbow blames herself, and has never left Twilight's side since.

Loss is a painful thing.