Marriage is the union of a man and a woman for the purpose of companionship and procreation. Mankind and the animals created on the fifth and sixth days were mostly created in male and female forms for the purpose of having offspring and becoming numerous. Within mankind, this union required the progression from child to adult and the leaving of ones own parents.
Jesus Christ Himself affirmed its truth when He gave His opinion on divorce: "the two shall become one... what God has joined together, let no man separate." [Consider Rewording] Any concessions later made in the Law were to alleviate suffering due to sin.
The word "marriage" as such does not show up much in the Bible. Many translations translate the word ownah as "duty of marriage" when discussing multiple wives. This word is only used here, and is probably related to living arrangements.
When discussing marriage in the New Testament, Jesus and others use forms of the word gamos which is used 16 times in all its forms. The origin of this word is unknown, for the Greek words for wife and husband are derived from the verb form.
The English "marriage" — the act of "marrying" — is derived from the Latin verb maritare meaning to provide with a mate. The root provides the noun forms maritus/a/um, depending on whether the mate is male, female or neutral.
The wording of the institution of marriage at the end of Genesis 2 clearly indicates that the design was for one man and one woman at one time. Although there was only one woman and one woman at the time, the idea of monogamous union between man and woman is found in the use of singular terms — the man is take one wife after leaving his parents.  This model was followed in all but one of the cases cited in the years before the Great Flood. When Noah went into the ark, he and his sons entered with their wives, for a total of eight people. When Abram was called out of Ur, he had his half-sister as his only wife. This indicates that in the close knit tribal group, the choice for wives was small. Though his father had Sarai by another wife, it may have only after Abram's mother had died. Abraham would indeed have his first child by a concubine, a servant owned by his wife, but Hagar was not a second wife. Abraham would wait until after the death of Sarah before taking Keturah to be his wife. Abraham's twin grandsons, Esau and Jacob, would both take two wives at one time — the first recorded polygamy in a space of about a thousand years.
The first case of multiple wives came in the line of Cain before the Flood. The man's name was Lamech, a proud man who sang a song to his two wives about his murdering two men. In the same pre-flood context, it is recorded that the "sons of God" saw the "daughters of men" and took whoever they wanted, perhaps even by violence. This loss of respect for the purpose of marriage did not go away after the Flood.
By the time of Abraham, years after the Great Flood, multiple wives had become part of the cultures that spread out from Babel. Though most of the secondary "wives" are called concubines, the grandson of Abraham, Jacob, accepted the fate thrust upon him by his father-in-law, the brother of his mother, namely Laban. The rivalry between the sisters, including the use of their slave girls to have children when they could not, serves as a warning against multiple wives.
This strife among women under the care of a single husband undoubtedly led to the Law against kings "multiplying wives." Unfortunately, when David fell into the trap of taking wives and concubines as a political maneuver, it proved disastrous as his sons fought him to take over the kingdom of Israel. His disregard for the Law in this regard was passed on to his son, Solomon, resulting in the latter taking 700 wives and 300 concubines, most of who were foreign wives that he "loved." These "lovers" lead to idolatry in the palace and near apostasy of the man known far and wide for his wisdom.
Love and Marriage
Early in his reign, Solomon penned his "love song" to his dark skinned "Shulamite" wife. One can only imagine this was his first wife, the daughter of the pharaoh of Egypt. This explicit book tells of a great love between a man and a woman.
During his reign, the son of David would pen several proverbs concerning the dangers of "strange" women and even the annoyance of a nagging wife. The last chapter of the Proverbs contains words from a king "Lemuel" who remembers his mother's words about a good wife. Finally, late in life, Solomon comes back to God, writing a warning against living for this world. In the middle of near despair, though, he remembers his youth, and the "wife of [his] youth." He admonishes his reader to enjoy life, especially the companionship of one's wife.
Multiple wives became rare by the time of the New Testament, but when Paul is giving the requirements for church leadership, he specifies "the husband of one wife," with the assumption being that more than one wife would disqualify a candidate. Following the doctrine of the "wife of God" in the prophets, Paul would use marriage as a metaphor for the Church as the "bride of Christ." In the Revelation, John would see the Church on display as the "bride of the Lamb."
However, marriage between persons in this world are not transferable into the next. When the Sadducees tried to trap Jesus with a hypothetical situation following the Law of Levirate marriage, Jesus scolded them for their ignorance. There is no "marriage" in heaven, according to Jesus, since the resurrected believer takes on a body that does not need to reproduce! Husbands, wives, and their children all become of one status — siblings — all living and worshiping God together.