that she's going around desperately hunting for cores to prevent becoming a Replacement, so it's not much of a stretch to say that she'd rather die as a human before becoming a Replacement. On the other hand, I don't think it was ever covered how other people respond to a human becoming a Replacement or how successfully a Replacement can fully replace the original. For some reason, I want to say that she also kills herself in a few loops because she can't bear the thought of him randomly murdering non-Replacement people after the phone breaks, but could be me wandering off in my own world. In both cases though, the idea of 'keeping your humanity' is present... though that opens up a whole different can of philosophical worms.
