If a chaste woman unfortunately marries a husband who is fallen, she should live separately from him. Similarly, a husband can separate himself from a woman who is not chaste according to the description of the sastra
SB Canto 7
A chaste woman should not be greedy, but satisfied in all circumstances. She must be very expert in handling household affairs and should be fully conversant with religious principles. She should speak pleasingly and truthfully and should be very careful and always clean and pure. Thus a chaste woman should engage with affection in the service of a husband who is not fallen.
According to the injunction of Yājñavalkya, an authority on religious principles, āśuddheḥ sampratikṣyo hi mahāpātaka-dūṣitaḥ. One is considered contaminated by the reactions of great sinful activities when one has not been purified according to the methods of the daśa-vidhā-saṁskāra. In Bhagavad-gītā, however, the Lord says, na māṁ duṣkṛtino mūḍhāḥ prapadyante narādhamāḥ: (BG 7.15) "Those miscreants who do not surrender unto Me are the lowest of mankind." The word narādhama means "nondevotee." Śrī Caitanya Mahāprabhu also said, yei bhaje sei baḍa, abhakta-hīna (CC Antya 4.67), chāra. Anyone who is a devotee is sinless. One who is not a devotee, however, is the most fallen and condemned. It is recommended, therefore, that a chaste wife not associate with a fallen husband. A fallen husband is one who is addicted to the four principles of sinful activity—namely illicit sex, meat-eating, gambling and intoxication. Specifically, if one is not a soul surrendered to the Supreme Personality of Godhead, he is understood to be contaminated. Thus a chaste woman is advised not to agree to serve such a husband. It is not that a chaste woman should be like a slave while her husband is narādhama, the lowest of men. Although the duties of a woman are different from those of a man, a chaste woman is not meant to serve a fallen husband. If her husband is fallen, it is recommended that she give up his association. Giving up the association of her husband does not mean, however, that a woman should marry again and thus indulge in prostitution. If a chaste woman unfortunately marries a husband who is fallen, she should live separately from him. Similarly, a husband can separate himself from a woman who is not chaste according to the description of the śāstra. The conclusion is that a husband should be a pure Vaiṣṇava and that a woman should be a chaste wife with all the symptoms described in this regard. Then both of them will be happy and make spiritual progress in Kṛṣṇa consciousness.