Kommentar zu Sotah 1:2

כיצד הוא מקנא לה אמר לה בפני שנים אל תדברי עם איש פלוני כו' – In the Gemara (Talmud Sotah 5b): He said in the presence of two [witnesses], “do not speak [with him]” and she speaks [with him], or “do not speak with him” and she secludes herself [with him], and it is nothing, and she is not prohibited neither to husband nor to [partaking of] Priest’s due–Terumah (if her husband is a Kohen). If he said to her, “do not seclude yourself [with him] and she spoke with him, for she was not yet secluded, she is permitted to her husband and she is permitted to eat Terumah if she is the wife of a Kohen. If she went with him into the house of seclusion and stayed with him [long enough] that she is impure, she is forbidden to her husband and forbidden to consume Terumah. And the measurement [of time] to become ritually impure is [the time it takes] to roast the egg of a chicken and to quaff it.

How does he warn her?
If he says to her in front of two [witnesses], “Do not speak with that man”, and she spoke with him, she is still permitted to her husband and permitted to eat terumah.
If she entered a private place with him and stayed with him a time sufficient for her to be defiled [by having sexual intercourse with him], she is forbidden to her husband and forbidden to eat terumah. If [her husband] died, she performs halitzah but cannot contract yibbum.
Yesterday’s mishnah taught that a husband cannot bring his wife to drink the Sotah waters unless he has first warned her not to seclude herself with a certain man. Today’s mishnah teaches what constitutes warning and what constitutes her transgression of his warning, such that she is brought to be tested.
Section one: The husband is overly strict in his warning. He suspects that she may be having an adulterous affair with a certain man, so he warns her in front of two witnesses not to even speak with this man. The mishnah teaches that even if she speaks with this man, she is not considered a Sotah. She is still permitted to her husband and, if her husband is a priest, she may still eat terumah. A man cannot prevent his wife from speaking to other men.
Section two: However, if he warned her, and she entered a secluded place with that man, then she is a Sotah, meaning a woman who must be tested before her innocence can be established. Since, she is now under the presumption of being an adulteress, she can no longer have intercourse with her husband. This is according to the rule that adultery forbids a woman from returning to her husband. If she is a priest’s wife, she can no longer eat terumah, since she may no longer be permitted to remain his wife. The woman is still his wife, but the normalcy of their marriage has ceased and therefore, to be strict, the halakhah forbids them to continue to act as man and wife. The fact that she still is his wife is evident from the last halakhah of the mishnah. If her husband died without children and she had a brother, she can no longer undergo the Sotah ritual. She is still required to have halitzah with her husband’s brother, because were she to have undergone the ritual she may have been found to be innocent, in which case the marriage would have returned to normal. However, she cannot have yibbum, because she may have actually been guilty. A wife prohibited to her husband as a Sotah is also prohibited to her yavam.
Note, that this last halakhah is the means by which the mishnah teaches that she is still married to her husband and that the fact that she is prohibited to him and cannot eat terumah are stringencies lest she is actually guilty.

אם מת חולצת ולא מתיבמת – but if her husband dies prior to causing her to drink [the bitter waters], she is released by Halitzah (i.e., she removes the shoe of her dead husband’s brother [and spits in his face]) and does not engage in a levirate marriage [with her dead husband’s brother], as it is written (Deuteronomy 24:2): “She leaves his household and becomes the wife of another man.” And they (i.e., the Rabbis) expound: “to another man” but not to the levir, and even though she is not permitted to a stranger without Halitzah, for just as if her husband were alive, she would not be permitted [to another man] without a Get–Jewish bill of divorce, so similarly, she is not permitted from the levir without Halizah.