Why would marriage be optional when God has a Son and commanded Adam and Eve to multiply and fill the whole world?

In the beginning when God instituted marriage, He commanded Adam and Eve to multiply and fill the whole world. Both the Old and New Testaments are initiated by marriage contexts, Adam and Eve were married and Jesus who is the savior is born into a marriage headed by Joseph and Mary. These two contexts show how marriage is of value in the scripture. *Genesis 1:28* >Then God blessed them, and God said to them, “Be fruitful and multiply; fill the earth and subdue it; have dominion over the fish of the sea, over the birds of the air, and over every living thing that moves on the earth.” When God said those words, it meant every human being who is capable of marriage should fulfill that obligation to populate the world, but then Paul taught that marriage is optional, and one should be married when overcome with passion. Why would marriage be optional when every man is commanded to leave his parents and be joined to his wife? *Genesis 2:24* >Therefore a man shall leave his father and mother and be joined to his wife, and they shall become one flesh. Genesis 2:24