Responsa su Ester 4:16

In the aforementioned responsum of Maharik, regarding Maharil’s question about whether woman who willingly committed adultery against her husband without knowing that it is forbidden is considered unwitting (shogeg), he responded: "In my opinion, it appears that she is not considered unwitting in order to be permitted to her husband, since she intended to betray her husband and cheat on him. After all, Scripture does not say “A man whose wife strays, and betrays God,” which would imply that the law applies only when she intends to violate a prohibition, but “and betrays him.”" Later he writes: "It also seems, in my humble opinion, that there is another proof that the matter does not depend on intent to violate a prohibition, for we learn in the first chapter of Megilla (15a): “‘If I am lost, I am lost’ (ka’asher avadeti avadeti; Esther 4:16): just as I lost my father’s house, so too I will lose you. Until now I have been compelled, but now I am willing.” We learn from this that from that time, she became forbidden to Mordechai. Now, it is clear that Esther did nothing prohibited, and there was not even a smidgen of transgression. Rather, she performed a great mitzva, for she saved all of Israel. Clearly that this is the case, for when she came before the king, the divine spirit rested upon her. But even so, she became forbidden to her husband, Mordechai, as a result of that willing act. Now we may reason a fortiori: if in that case, where there was not a smidgen of transgression, and, on the contrary, she did a mitzva, and yet she was still forbidden to her husband Mordechai, then certainly a woman who committed adultery against her husband, even if she does not know that this is prohibited, is forbidden to him because she nevertheless transgressed, and needs atonement, and is liable to bring an offering."