From their argument, it sounds as if she took the death of Catarina Claes-san. If she realized that she was unable to stop someone from dying again, why would she continue to participate in a system that would just lead to more death?

[The voice had been familiar and unexpected, so she can't brush her reaction off as something less than recognition. He'd see right through some explanation that she hadn't expected the recreations to feel so real. So -]

No, I can't say that I knew her, exactly. More accurately, I would describe her as a friend of someone I was much more familiar with.