This bit in particular may help
In a parallel passage which also emphasizes the truth that God considers marriage to be a covenant, the prophet Malachi explains to his Jewish audience why Jehovah was paying no attention and taking no pleasure in their offerings, writing...
Yet you say, ?For what reason?? Because Jehovah has been a witness (thus God is able to speak of their violation of covenant since He had witnessed their matrimonial pledges of mutual loyalty) between you and the wife of your youth, against whom you have dealt treacherously, though she is your companion (this Hebrew word is derived from the root habar meaning to fasten together, to join together or to unite and in context implies harmony and working together to achieve life?s goals while sharing the hardships, pain and joys; LXX = koinonos = derived from koinos which means that which is in common or shared by all. Koinonos thus describes one who participates with another in an enterprise or matter of joint concern!) and your wife by covenant (beriyth = a serious, solemn, binding oath). (Malachi 2:14)
God goes on to add...
I hate divorce," says the LORD, the God of Israel, "and him who covers his garment with wrong," says the LORD of hosts. "So take heed to your spirit, that you do not deal treacherously. (Malachi 2:16)
The same verse in the Amplified translation reads...
Yet you ask, 'Why does He reject it?' Because the Lord was witness [to the covenant made at your marriage] between you and the wife of your youth, against whom you have dealt treacherously (this verb conveys the idea of unfaithfulness in relationships like marriage, as in Jeremiah 3:20) and to whom you were faithless. Yet she is your companion and the wife of your covenant [made by your marriage vows]. (Bolding added)
So why did God reject Israel's "worship" as "worthless"? In this context it was because they had not been faithful to their marriage covenant! Is God serious about the covenant of marriage! The tragedy is that today so many view marriage as a contract, (a business arrangement for the supply of goods or services at a fixed price: Merriam-Webster) not as a covenant founded on Biblical principles. If the contract does not work out, the parties involved mutually agree to terminate the agreement and go their separate ways, and a divorce ensues. Time Magazine had an article in 1993 stating that it was easier in the United States to walk away from a marriage than from a commitment to purchase a used car! This is a tragic statement! Most contracts cannot be unilaterally abrogated, but marriages in open minded America can be terminated by practically anyone at any time, and without cause.
John MacArthur comments that this verse in Malachi
accentuated the iniquity (of violating their marriage vows) by mentioning the legally binding nature of the marriage contract, a covenant made before God as Witness. (MacArthur, J.: The MacArthur Study Bible Nashville: Word or Logos)
Thomas Constable adds that
The marriage relationship is a covenant relationship, and those who break their vows should not expect God to bless them. God Himself acted as a witness when the couple made their covenant of marriage in their youth." (Constable's Expository Notes on the Bible)
R C Sproul adds that...
Marriages are our closest human relationships and should emulate most nearly our fellowship with God. The rise and fall of marriage in a society acts as a barometer by which to measure the godliness of that culture...
First, marriage is a covenant. This is the keystone of the analogy Paul makes in Ephesians 5 between earthly marriage and the relationship between Christ and the church. The bond between Jesus and His bride forms the New Covenant, the spiritual reality of which human marriages are a type. Malachi 2:14 explicitly makes the connection between marriage and covenant. But what does that mean? We should consider several aspects of a covenant.
First, a covenant establishes a bond between two parties, in this case the husband and wife. At the heart of this bond is a promise, the promise of faithfulness.
Second, a covenant establishes obligations. A primary obligation in marriage is fidelity. The husband is obligated to lead his wife in love, and she is obligated to submit to him in the fear of the Lord.
Third, a covenant is public. It is contracted before witnesses. There is a great difference between the whispered pledges of a boy in the back seat of a car and the solemn vows of a young man before God and witnesses in the ceremony of holy matrimony. This public character of the covenant means that marriage is a social institution that society has an interest in preserving. As an institution, marriage is regulated by the Word of God. That the marriage covenant is not simply a private affair becomes clear when we consider divorce. Divorce wrecks the lives of children. Divorce destroys peace of mind and damages the effectiveness of employees. Divorce upsets friends and family. For Christians, an ungodly divorce forces the elders of the church to exercise discipline. Marriage is the closest possible relationship between two depraved human beings. Thus, marriage is potentially a wonder of grace or the scene of intense pain."