User blog comment:Zathronas/Speculative author: Who is Summer Rose?/@comment-6830001-20140809121822/@comment-96.254.157.84-20140809151032

Summer did die for a reason, most likely, but we don't know if that means she sacrificed herself for someone, fought as long as she could before she was overwhelmed, or was stabbed in the back by a friend for trying to do something she believed was good.

I don't think she sacrificed herself for Ruby because if the song is any indication, someone told Ruby that Summer was dead rather than seeing it herself.

Just speculating.