That is, perhaps we are talking about a pregnant woman, and the husband suspects that he is not the father, and so is jealous of his wife. See the following points which might bolster that reading.
There is a focus on "besides your husband." Thus,
Indeed, earlier, when spelling out the offense, we have:
derashot from it. Is not וְשָׁכַב אִישׁ אֹתָהּ sufficient? But perhaps שִׁכְבַת-זֶרַע actually means a shechiva which yields zera, progeny.
Then, in the curses, we do not see that she dies. Rather,
Indeed, perhaps this could be an explanation of the terming of the waters mei hamarim. This is admittedly really out there, but contrast to Ruth 1, where Naomi calls herself Mara because of the loss of her sons:
|כח וְאִם-לֹא נִטְמְאָה הָאִשָּׁה, וּטְהֹרָה הִוא--וְנִקְּתָה, וְנִזְרְעָה זָרַע.||28 And if the woman be not defiled, but be clean; then she shall be cleared, and shall conceive seed.|
I would suggest that the idea is that she is pregnant. And since her thigh did not fall and her belly did not swell -- she did not abort the fetus, she will carry the baby to full term and וְנִזְרְעָה זָרַע, have a child.