1,814. Ex-Wives That a Man May Not Remarry

Hilchos Geirushin 10:12

Let’s say that a man divorces his wife because she’s developed a bad reputation or is careless regarding vows. He is told to inform the woman that he’s divorcing her as a rebuke, and he’s also informed that he cannot remarry her in such a case. The reason that he’s not allowed to remarry her is an enactment against the possibility that she might marry someone else, repent her misdeeds and live an upright lifestyle. Her first husband might then say that had he known, he wouldn’t have divorced her; this would resemble a divorce predicated on a condition that wasn’t met, which could retroactively invalidate a get. The husband is therefore informed that he must divorce her decisively, fully aware that he can never remarry her. However, if he violates the law and remarries her before she is betrothed to anyone else, then he is not obligated to divorce her.

Hilchos Geirushin 10:13

If a man divorces his wife because she is congenitally infertile or because she always has menstrual bleeding during intercourse, he should never remarry her. This is out of concern that she marry someone else and have children or be healed from her condition, causing her first husband to say that had he known, he wouldn’t have divorced her. This might suggest that her get is invalidated, which would make her children illegitimate. However, if he violated the law and remarried her, he is not obligated to divorce her.