Malachi finally names the specific sin causing God’s silence: these men were divorcing the wives of their youth. Notice the phrase “the LORD was witness.” Marriage in Scripture is never simply a private arrangement between two people. It is a covenant made in the presence of God, who stands as witness and guarantor of the bond. That is why breaking it is called faithlessness, the same word used of Israel’s idolatry, rather than simply disappointment or incompatibility.
The phrase “wife of your youth” and the word translated “companion” point to a relationship built over years, someone who grew up alongside you, not a person you can trade in when the relationship grows difficult. In the culture of Malachi’s day, a divorced woman often had no rights, no protection, and no means of support. To divorce her publicly was to leave her socially and economically destitute. That is why Malachi will go on to say this sin covers a man’s garment with violence.
Paul roots the seriousness of marriage in the same reality centuries later in Ephesians 5:25-33, comparing a husband’s love for his wife to Christ’s love for the church. A marriage covenant is never just about two people. It is a living picture of God’s own faithfulness to his people, which is exactly why treating it as disposable does such damage, both to the people involved and to the testimony of the gospel itself.