Then shall the man be guiltless from iniquity
Which otherwise he would not, by conniving at her loose way of living, and not reproving her for it, and bringing her either to repentance or punishment; and retaining and encouraging jealousy in his mind, without declaring it, and his reasons for it: the sense of the passage seems to be, that when a man had any ground for his suspicion and jealousy, and he proceeded according as this law directs, whether his wife was guilty or not guilty, no sin was chargeable on him, or blame to be laid to him, or punishment inflicted on him:
and the woman shall bear her iniquity;
the punishment of it, through the effects of the bitter waters upon her, if guilty; nor was her husband chargeable with her death, she justly brought it on herself: or if not guilty, yet as she had by some unbecoming behaviour raised such a suspicion in him, nor would she be reclaimed, though warned to the contrary, she for it justly bore the infamy of such a process; which was such, as Maimonides says F16, that innocent women would give all that they had to escape it, and reckoned death itself more agreeable than that, as to be served as such a woman was; (See Gill on Numbers 5:18).
F16 Moreh Nevochim, par. 3. c. 49. p. 499.