1,676. Dissolving Marriages of Secondary Prohibitions
Hilchos Ishus 24:3
Since the women in the previous halacha are not paid the baseline amount of the kesubah, why are they paid the additional amount? The reason is because the baseline amount was enacted by the Sages so that a man would not consider divorce to be a trivial thing. Since he was unaware of the situations in the previous halacha, she is not paid the baseline amount of the kesubah. Regarding the additional amount, however, the wife kept her part of the marital agreement for as long as she wanted to perpetuate the relationship. She satisfied his conjugal needs and is willing to keep the marriage going; it is the Torah that requires that the marriage be dissolved against her will. She is therefore paid the additional amount because she is not responsible for becoming prohibited after the marriage; she was actually prohibited even before the marriage.
Hilchos Ishus 24:4
One might ask why, in the case of a secondary prohibition relationship, the Sages didn’t differentiate between when the situation was known before a marriage and when it wasn’t known until afterwards. Rather, they ruled that in all such cases the wife isn’t paid the baseline amount of the kesubah. This is because these secondary prohibitions are a rabbinic enactment. Accordingly, the Sages saw the need to strengthen it. However, if a man married a woman who was prohibited because of a Torah prohibition and he was aware of the situation at the time of the marriage, then she is paid the value of her kesubah. If one marries a woman who is prohibited by a positive Torah commandment, she is paid her kesubah whether or not he was aware of the situation at the time of the marriage. This is because if a man is aware that a woman is prohibited by a Torah prohibition, then he is choosing to incur this loss, while prohibitions based on positive commandments are much less severe. In both of these cases, the women are entitled to maintenance in the event of the husband’s death. Similarly, if they had to borrow money to pay for their own maintenance, the husband is obligated to repay the debt. When a husband is forced to divorce a wife because of such situations, he must repay her for the benefit that he derived from her property.