Commentary for Numbers 30:7

ואם היו תהיה לאיש AND IF SHE BECOMES A MAN’S — (a phrase used for marriage). This refers to a woman who becomes betrothed (ארוסה). Or perhaps this is not so, but it refers to a married woman (one who has joined her husband; cf. Rashi on Leviticus 21:9). When, however, it says, (v. 11) “And if she vowed in her husband’s house”, it is evident that a married woman is being spoken of there, and here, therefore, the text is speaking of one who has been only betrothed. And it (the separate mention of her) is intended to make a different rule about her — that her father and her husband must annul her vow: if the father annulled and the husband did not annul, or the husband annulled and the father did not annul, then this vow is not regarded as annulled, and it is not necessary to state (and it is a matter of course) that if one of them confirmed the vow the other has no power to annul it (Sifrei Bamidbar 153:7; Nedarim 67a).

AND IF SHE WERE AT ALL [BETROTHED] TO A MAN, AND THERE ARE VOWS UPON HER. In the opinion of our Rabbis⁴⁵Nedarim 71a. Scripture [here] is saying: “and if she, this woman [mentioned above in Verses 4-6] were at all [betrothed] to a man, and bound herself by a bond, being in her father’s house, in her youth⁴⁶Verse 4. — and there are vows upon her, meaning that her father had not heard them, so that they were neither annulled nor confirmed, and her [betrothed] husband hears them as well [as her father who hears them now when she is betrothed], then he makes void her vow,⁴⁷Verse 9. signifying that he also joins [now] with the father in annulling her vows [that are upon her].”

But perhaps to a “nesuah.” Meaning that although the plain understanding of הויה [lit. "being" having the connotation of marriage] refers to kiddushin [betrothal], nonetheless, we also find הויה referring to relations as in “his virgin [sister] who is close to him, who was not היתה ["married"] to a man” (Vayikra 21:3) where [היתה] refers to relations, meaning she was a nesuah. Thus, I would have said that הויה here also refers to relations and a she was a nesuah, such that both the father and the husband would annul her vow. However “when it says…”