פירוש על יומא 163:13

Just as with the pregnant woman, permission is given – to the savior to save her from this rape with the life of this rapist. Kill him only until he comes upon her, as it is written: there is nobody to save her, and if there is a savior, they should save her any way possible.

Let the murderer be killed and not transgress – if they said to him kill your fellow, and if you don’t I will kill you, let him be killed and not transgress as it is explained later (in the text)

So too a betrothed woman – if they say “rape the woman who is engaged to your fellow or you will be killed," he should be killed. But she is not commanded to give up her life, because she does nothing. She is merely like the ground, the proof of the matter is Esther.