To be honest, despite her being like this, its understandable that she'd do this. You having to die...then your friend gets the happy ending. Its sad, really...the more I think about, the more I understand. She just wants to have the same life as Beatrice but she just has he wrong mindset to things. *Insert flashbacks*
Stumbled upon this on another Manga website and there were only 6 chapters there, I went here instead to see if it was updated and to my surprise, it was COMPLETED. The story was so interesting, it's sad to see it end so quickly QnQ.