טוֹבִ֥ים הַשְּׁנַ֖יִם מִן־הָאֶחָ֑ד אֲשֶׁ֧ר יֵשׁ־לָהֶ֛ם שָׂכָ֥ר ט֖וֹב בַּעֲמָלָֽם׃
두 사람이 한 사람보다 나음은 저희가 수고함으로 좋은 상을 얻을 것임이라
Or HaChaim
There remains the difficulty that according to what Moses told Aaron only one person had to die in order to demonstrate to the people that G'd is sanctified by someone close to Him. Why did both sons die? After all, according to Moses' own words he had only been in doubt which one would be the victim. He never considered that there could be two or more victims to demonstrate the point G'd wanted to make. Besides, whence did Moses know that Nadav and Avihu were of greater stature than either Aaron or himself? Seeing that G'd had mentioned one person as dying, it is plausible that that one person was of greater stature than either Moses or Aaron. Why would I assume that both were greater? In fact it seems strange that two had to take the place of one, i.e. either Moses or Aaron? If so they were not greater than Moses or Aaron individually. One can certainly not argue that in this case Solomon's rule (Kohelet 4,9) applies that טובים השנים מן האחד, "that two are better than one?"
Radak
אעשה לו עזר, an assistant when the need should arise. Solomon, in Kohelet 4,9, paraphrased this when he wrote: טובים השנים מן האחד, “two are better than one alone.” Furthermore, woman was a necessity if man was to leave offspring behind to insure the continuity of his species.
Or HaChaim
It is in keeping with G'd's propensity for preparing everything good ahead of time, and providing many more opportunities for man to do good than evil. However, we must ask why He separated the two bodies enabling Eve to fall victim to the temptation by the serpent? This leads us to examine the cause of Adam's (Eve) sin, what happened to him and all of mankind as a result. We have found that woman became the cause of all that the world lost because the serpent prevailed over her in a match of wits. This occurred because Adam was not at her side at the time of Eve's encounter with the serpent. He was asleep as a result of having had marital relations with his wife (Bereshit Rabbah 19,3). Another version in the Midrash there suggests that G'd had taken him on a tour of the earth. As a result the serpent encountered Eve on her own and succeeded in seducing her. If the Torah had reported man's creation and the subsequent separation of Eve's body sequentially, without interposing Adam's experiences on earth in the interval, many people would have argued that what happened was all G'd's fault. They would have said that if G'd had not separated her body from that of her husband, thereby making a drastic change in what He had created originally, the serpent would never have had a chance to seduce Eve. In order to forestall such an argument the Torah tells us first the reason that G'd separated Eve's body from Adam's, i.e. in answer to Adam's own request. His observations of how the animals lived, male and female as separate bodies, had made him desirous of a similar arrangement. G'd had only the best of intentions, as usual. This is also the reason the Torah told us already at the outset that man was equipped to procreate from the moment he was created. Being one and the same body obviously had some of the same disadvantages as being a Siamese twin. G'd therefore decided it would be better for man's helpmate to be כנגדו, an appropriate complement, rather than the other half of his body. In this way she could be a help to him at all times instead of being a hindrance on occasion. Eve's being a separate body was not dictated by Adam's need to procreate. Seeing that the separation of her body served only to please Adam we must ask why none of the other creatures could have been trained to perform that task for Adam while leaving Eve in the state she had been created. The Torah therefore describes in verses 19 and 20 that Adam did indeed search for a suitable helpmate amongst all the other creatures but did not find one that was acceptable to him. Naming the animals, i.e. identifying their essence, was part of that search for a suitable helpmate. Eve's existence as a separate body from Adam had therefore become mandatory from Adam's point of view. It is totally incorrect to blame G'd for subsequent developments, such as Eve finding herself temporarily alone, facing an evil influence whose existence she had been quite unaware of. The Torah's report about both Adam's and Eve's innocence, i.e. their lack of shame at being nude, are all facts the Torah supplies to enable us to better understand the causes that led to the sin. Human relationships are based on people facing each other, i.e. כנגדו. The Torah describes Adam's profound joy when he finally beheld the partner who up until then had been hidden from him, i.e. had faced backwards. From G'd's point of view the original arrangement was perfectly acceptable, He had not created an imperfect human species. Any change was entirely in response to Adam's frame of mind, to accomodate him. Our sages have supplied us with numerous reasons why G'd did not create an entirely new human being to serve as Adam's helpmate. When Solomon told us in Kohelet (4,9) טובים השנים מן האחד, that two are better than one, that they can help each other, this has nothing to do with G'd having created man's form in such a way that he could have impregnated the wife which was part of him but facing backwards.