Spencer was not just anybody to her. He was her love, her soulmate, her support, and her home. It was him who told and gave her the courage to love again despite the pain and obstacles.
It was him that help her believe that there was real love and hope in the world, that the world was just made of darkness and betrayal. It was him that helped her understand that love can conquer any dark force. He was the one that loved her more than his own life, the one that would do anything to protect her.
It was only with him when she felt content and happy.
How could she leave him?