Likutei Moharan, Part II 32:3/ליקוטי מוהר"ן·תנינא ל״ב:ג׳

13. And know! “the ruach of our nostrils, m’shiach of God” becomes a spirit of jealousy that grows increasingly more zealous. Wherever it finds immorality, [this ruach] becomes a jealous spirit and, on account of its considerable sanctity and purity, zealously protests it. Sometimes, [the ruach] zealously protests “and she had become defiled, or a spirit of jealousy may come over him… but she had not become defiled” (Numbers 5:14). Because of its tremendous holiness and purity, even if she has not become defiled, it zealously protests solely on account of the seclusion, which is considered a blemish relative to the jealous spirit’s tremendous purity. And on occasion this leads to divorce.

2This is why the divorce document is called “a sefer of separation” (Deuteronomy 24:1), because it is produced by the sefer (book) upon which the spirit of Mashiach, the spirit of jealousy, resides. Alternatively, he makes her drink the “bitter waters,” which examine “if she has become defiled…” (Numbers 5:27). But if not, then, on the contrary, “she shall be proven innocent and she will bear seed…” (ibid. :28).