Some translate it an adulteress under her husband's roof, and tcht, thecheth, signifies "instead of:" and they explain it thus, that adulteresses do not divorce themselves from their husbands when they violate the marriage bond, but always remain at home for the purpose of admitting strangers; and they think the people's crime increased by this comparison, that they not only acted deceitfully towards God, but openly revolted from him, and left his home; for many shameless women remain at home, and hide their crimes as far as they can; but when a woman deserts her husband and children, then her case is most deplorable: they think, therefore, that the Prophet is here exaggerating the divorce or revolt of the people from God; but the sense seems better simply to compare them to an adulteress who admits strangers in her husband's stead: thou art says he, an adulteress who has sent for strange lovers instead of thy husband: for a woman married to a liberal husband is treated by him honorably; and if she seeks lovers from all sides, she is induced by neither avarice nor covetousness, but by her own lusts. In fine, as the Prophet lately said that they despised all gain through being blinded by their appetites, so he now says they were like an adulteress who rejects her husband; and not only so, but throws herself into the protection of others, while she has an honorable and happy home.

But as a wife that committeth adultery,.... Who has a husband, and is provided for with all the necessaries of life, with food and clothing; and so has no need to prostitute herself for a livelihood, as common strumpets do; but does it purely for the satiating of her lust: and such were the people of the Jews, they were married to the Lord, who took care of them, and provided everything for them, and acted the part of a husband to them; so that it was the weakness of their hearts, and the strength of their corruptions, which led them to depart from him, and commit idolatry; which in them was adultery, while the sin of the Gentiles was as simple fornication:
which taketh strangers instead of her husband; that takes other men into her bed instead of her husband, not for the sake of gain, but lust; and this was the case of the Jews, who were a wicked people, an idolatrous generation; who took strange gods to worship instead of the true God, who had been a husband to them, Jeremiah 31:32.

instead of her husband--referring to Numbers 5:19-20, Numbers 5:29. FAIRBAIRN translates, "whilst under her husband."