(Bamidbar 5:22) "to swell the belly and to make fall the thigh": R. Yossi Haglili says: This refers to the belly and the thigh of the adulterer. You say the belly and the thigh of the adulterer; but (perhaps it refers to) the belly and the thigh of the adulteress! — (This cannot be, for) [5:21] "… causing your thigh to fall and your belly to swell" already refers to the adulteress. How, then, am I to understand "to swell the belly and to make fall the thigh"?
As referring to the adulterer, Scripture apprising us that just as punishment overtakes her, so, it overtakes him. Now does this not follow a fortiori, viz.: If re the attribute of punishment, the "weaker" attribute (of the Holy One Blessed be He), if one brings misfortune to his neighbor, he suffers likewise, then re the attribute of benefaction, (the stronger attribute, if one bring benefit to his neighbor,) how much more so (is he benefitted himself!) (Ibid. 22) "and the woman shall say 'Amen,' 'Amen.'": "Amen" that I have not become unclean; "Amen" that I will not become unclean, (in which instance the bitter waters operate retroactively).
These are the words of R. Meir. And the sags do not agree, (but they say) "Amen" that I have not become unclean (i.e., acceptance of the oath) and ("Amen" that) if I have become unclean, they (the waters) should enter her (i.e., acceptance of the curse). "Amen" in respect to this man (the suspected adulterer); "Amen" in respect to any other man; "Amen" when betrothed — "Amen" when married; "Amen" when awaiting levirate marriage — "Amen" after levirate marriage.
This is the rule: For a woman to be lived with and (thereby) to be forbidden (to her husband), the stipulated conditions must be those of that time (i.e., while she is still married to him [and not, e.g., before betrothal or after divorce]).