And again, verily I say unto you, that whoso forbiddeth to marry is not ordained of God, for marriage is ordained of God unto man.
Ordained of God means that it is established by God or ordered by God. Now, I am not sure if it is officially doctrine of the church, but that sounds like it might be a commandment. Of course, the most important part, is that it is there for us. God has established the family as a primary organization. President Benson,
The Church of Jesus Christ of Latter-day Saints views the family as the most important organization in time and all eternity. The Church teaches that everything should center in and around the family. It stresses that the preservation of family life in time and eternity takes precedence above all other interests.
The Teachings of Ezra Taft Benson, 489.
The family takes precedence above ALL other interests! We learn this early on in the Book of Mormon from 1 Nephi 7,
1 And now I would that ye might know, that after my father, Lehi, had made an end of prophesying concerning his seed, it came to pass that the Lord spake unto him again, saying that it was not meet for him, Lehi, that he should take his family into the wilderness alone; but that his sons should take daughters to wife, that they might raise up seed unto the Lord in the land of promise.
2 And it came to pass that the Lord commanded him that I, Nephi, and my brethren, should again return unto the land of Jerusalem, and bring down Ishmael and his family into the wilderness.
Nephi tells us that the Lord commanded Lehi that the family of Ishmael should be fetched from Jerusalem in order for Lehi’s sons to marry Ishmael’s daughters. We learn from the First Presidency and the Quorum of the Twelve by way of The Family: A Proclamation to the World
marriage between a man and a woman is ordained of God and […] the family is central to the Creator’s plan for the eternal destiny of His children.
In order to fulfill our eternal destiny, as children of our Father in Heaven, we must marry.