“If a man vows a vow to the LORD … he shall not break his word” (v2). In the Old Testament, vows were sacred, voluntary promises that an individual made to God to act or to live in a certain way (like a Nazarite vow, or Hannah’s vow about her firstborn). The only people allowed to break vows were daughters or wives whose household authority (father or husband in those days) objected. They could not be expected to fulfill a vow that caused conflict in their home (v3-12).
God wants us to be at peace with Him so that we can also live in peace with one another. Radical devotion to Him causes us to love others more, not less.