תָּנוּ רַבָּנַן אֲשֶׁר תִּשְׂטֶה אִשָּׁה תַּחַת אִישָׁהּ לְהַקִּישׁ אִישׁ לְאִשָּׁה וְאִשָּׁה לְאִישׁ לְמַאי הִלְכְתָא אָמַר רַב שֵׁשֶׁת כְּשֵׁם שֶׁאִם הוּא סוֹמֵא לֹא הָיָה מַשְׁקָהּ דִּכְתִיב וְנֶעְלַם מֵעֵינֵי אִישָׁהּ כָּךְ הִיא אִם הָיְתָה סוֹמָא לֹא הָיְתָה שׁוֹתָה רַב אָשֵׁי אָמַר כְּשֵׁם שֶׁחִיגֶּרֶת וְגִידֶּמֶת לֹא הָיְתָה שׁוֹתָה דִּכְתִיב

The Sages taught that the verse: “This is the law of jealousy, when a wife, while under her husband, goes astray and is defiled” (Numbers 5:29), is superfluous, and serves to compare a man to a woman and a woman to a man. The Gemara asks: With regard to what halakha is this comparison necessary? Rav Sheshes says: This teaches that just as if the husband was blind he would not have her drink, as it is written: “And it was hidden from the eyes of her husband” (Numbers 5:13), indicating that the sota ritual applies only if the husband was capable of seeing her infidelity but did not do so; so too, with regard to the woman, if she were blind, she would not drink. Rav Ashi also says: Just as a lame woman and a woman without hands would not drink, as it is written:

וְהֶעֱמִיד הַכֹּהֵן אֶת הָאִשָּׁה לִפְנֵי ה׳ וְנָתַן עַל כַּפֶּיהָ כָּךְ הוּא אִם הָיָה חִיגֵּר אוֹ גִידֵּם לֹא הָיָה מַשְׁקָהּ מָר בַּר רַב אָשֵׁי אָמַר כְּשֵׁם שֶׁאִילֶּמֶת לֹא הָיְתָה שׁוֹתָה דִּכְתִיב וְאָמְרָה הָאִשָּׁה אָמֵן אָמֵן כָּךְ הוּא אִם הָיָה אִילֵּם לֹא הָיָה מַשְׁקָהּ

“And the priest shall stand the woman before the Lord…and place the meal-offering of memorial in her hands” (Numbers 5:18), indicating that if she is unable to stand up straight or if she does not have hands with which to accept the offering, then she does not drink; so too, if the husband were lame or without hands, he would not cause his wife to drink. Mar Bar Rav Ashi says: Just as a mute woman would not drink, as it is written: “And the woman shall say: Amen, Amen” (Numbers 5:22), indicating that she must be able to speak; so too, if the husband were mute, he would not cause his wife to drink.

Our Gemara on Amud Aleph discusses a series of inferences and derashos that teach us disqualifications  for the Sotah Ordeal based on various physical handicaps, and that even if one spouse has them, it disqualifies both of them.  Such persons will not drink from the Bitter Watters, and if there is a witness that she violated the injunction against being secluded with whom she was warned not to, she will remain forbidden:

The Mussar Hamishna (Rav Yehuda Leib Ginsburg, 1888–1946) says the reason for this equivalence is that any time there is a disparity and physical handicap on one side or the other in a marriage, there is greater likelihood of strife, and thus we give more weight to the single witness that she was alone with her accused paramour. That is, we have more doubt that she is innocent so the Torah doesn’t require any test and we assume she is guilty from the strong circumstantial evidence. Rav Hirsh tweaks this idea. He says, really when one spouse or the other has a disability it could increase connection via the dependence. However, since this woman conducted herself in an immodest way it shows there is contempt in the relationship on one side or the other stemming from the handicaps, and the relationship cannot be saved.

It occurs to me that there is a message and rebuke in the exemption.  Each spouse should ideally carry the other spouse's emotional burdens and challenges.  It is as if the Torah is saying, “You BOTH SHOULD have treated each other’s burden as if it was yours, so now we will judge you on that basis.”