Good for Nureba she was finally able to acknowledge that Midari is despite everything she's done to and with her that she is truly Ayame's best girl. Another point to remember is that despite all of Midari antics she's more into self harm or getting others to inflict things to her, she will threaten folks and may strong arm a little but her gambles seem to focus primarily on any negative consequences happening only to her. She likely could just be trying to frighten Ayame into shooting her for real, trying to play a game of chicken with Ayame she hopes to lose.
