She starts sobbing again as soon as Elsa's lips touch her forehead. As soon as warm arms come to wrap around her shoulders and pull her as close as possible, and then even closer.
Elsa's silent, even as several tears leak over her own cheeks. This moment is for Anna, and she wishes she were able to help ease her friend's suffering.
But, there's nothing. Anna has lived with this guilt for a very long time, and there's Elsa can't do anything assuage it.
It takes her a very long time to fall asleep.