Song Qingxiao noticed that number two—the office lady—wore an unmistakable grin because of the doctor's choice. After the situation progressed to that stage, they were past the point of no return. No one would be willing to show mercy.
They were too focused on preserving their own lives.
Even though only the last person alive could leave the place, her alliance with number two was highly fragile. Hence, she could only focus on saving her own life. She could not rely on someone else to save her.
Running away was not an option for Song Qingxiao. If she gave up and ran away then, the office lady would retreat as well, and their impromptu alliance would be completely destroyed. It would be highly disadvantageous for her.