The LORD God said, “It is not good for the man to be alone. I will make a helper suitable for him.”
Now the LORD God had formed out of the ground all the wild animals and all the birds in the sky. He brought them to the man to see what he would name them; and whatever the man called each living creature, that was its name. So the man gave names to all the livestock, the birds in the sky and all the wild animals. But for Adam no suitable helper was found. GENESIS 2:18-20
It's interesting to know that God says it's not good for man to be alone. He then shows Adam how all the animals are in pairs. One would think Adam would begin to feel something is missing in his life, Perhaps he began to feel alone, something was missing for him since he did not have a mate like all the animals did.
Of course it was was God's intention to always bring Eve into his life after Adam experienced living alone.
Adam needed a complement to complete him. Taking out of Adam's own body God made a woman to do just that. He made someone just like him, only the opposite in many ways. Together they formed a complete man now. God called them Adam. He gave them one identity, comprised of male and female. A man usually represents strength, leadership ship, where the woman represents gentleness and caring. Together they were to rule with all of those qualities combined.
Someone to be his complement must come from within, and be of the same kind. The word "complement" means that which fills up, and there could be no filling up if that place we're not first made vacant. Adam, before the woman was taken from him, was complete in himself; afterwards the woman made him complete. John H. Essex
This earthly reality is also a shadow of a heavenly reality concerning Christ and the Ecclesia.
For no one at any time hates his own flesh, but is nourishing and cherishing it, as Christ also, the ecclesia, seeing that we are members of His body. Corresponding to this a man will be leaving father and mother and will be joining to his wife and the two will be one flesh. Ephesians 5:29-31
In ch1 v26, God wanted man to "have dominion over" the fish, the birds, the animals of the earth, and indeed living things in general. I suggest that the "helper" was necessary for this task. How does that work? Well, man cannot have dominion over the earth without multiplying in number. This explains why the command "be fruitful and multiply, and fill the earth" comes next (v28) and leads directly into "and subdue it and have dominion over..." etc. And it is not possible for mankind to multiply in number without having a female component. That explains the rapid addition of the woman to the scene (ch2 vv21-23). The immediate consequence of the existence of Woman is the principle that men and women should come together; "Therefore a man leaves his father and mother and cleaves to his wife and they become one flesh" (ch2 v24). The chain of logic is completed in Malachi where God explains why he hates divorce; "Has not the one God made and sustained for us the spirit of life? And what does he desire? Godly offspring. So take heed to yourselves and let none be faithless to the wife of his youth" (Malachi ch2 v15, RSV) The conclusion is that God's intention in providing two genders for the human race is that they should come together and have children. This HELPS humanity to fulfil God's purpose that we should increase and multiply and have dominion over the earth.
I should add, for greater clarity, that ch2 v24 was quoted for the sake of "a man leaves his father and mother and cleaves to his wife". This is the action which leads into the multiplication of individual human bodies, and makes filling the earth possible. Perhaps God might have done it another way, but he chose to do it this way.
Starting at the beginning
The OP's question is best answered with reference to the earlier narrative concerning the creation of woman in Gen. 1 - namely that God created humans as both male and female, in God's own image. So, God created both man and woman and blessed them to be fruitful and multiply. Then God declared his entire creation to be "very good."
So God created man in his own image, in the image of God he created him; male and female he created them... And God blessed them, and God said to them, “Be fruitful and multiply... And God saw everything that he had made, and behold, it was very good. (Gen. 1:27-31)
Why Eve's absence was "not good"
In Gen. 2, on the other hand, the Lord creates Adam out of the dust of the earth, places him in the Garden of Eden, commands him not to eat of the forbidden fruit, and has Adam name the animals. Seeing that Adam has no helper, the Lord finally says "it is not good that the man shall be alone."
If we take the two narratives together, we see that God had already declared the creation of man and woman together as "very good." Moreover, this male-female pair was created in the "image of God." God had blessed them and commanded them to "be fruitful and multiply." Adam alone could not fulfill this blessing/commandment, nor could he alone be the complete "image of God" without Eve. Thus, it is only logical that God would see Adam's solitary state in Gen. 2 as "not good."
Since "God" reveals him/her self as Alpha and Omega as well as beyond 'them as Ein Sof it's only necessary to study more deeply to come to an answer suited to ones individual capabilities at any particular time. At another stage in ones 'understanding' one might well come to an explantion suited to ones capabilities at this other phase.