Numbers 30 begins with the Lord stating that when a man made a vow, he had to keep it, but if a woman made a vow, if she still lived at home, her father could overrule her, and in verses 10-15, the Lord made the same provision for a married woman, that her husband could overrule her.

However, if neither her father nor her husband overruled her, then she had to keep her vow, and the Lord fully expects us to keep our vows, whatever they may be, even if it hurts us, for it is written in Psalm 15,

Lord, who may abide in Your tabernacle?
Who may dwell in Your holy hill? …
He who swears to his own hurt and does not change…
(Psalm 15).