Sforno on Genesis 2:18/ספורנו על בראשית ב׳:י״ח

1לא טוב היות האדם לבדו, the purpose of the human species on earth will not be achieved while man who is supposed to reflect the divine image will be left to personally carry out all the menial tasks of daily life on earth by being solitary.

2עזר כנגדו, a helpmate who will be equal to him, also reflecting the divine image. This is essential for him if he is to know what precisely his needs are and so that he can meet them in time. The reason why the Torah added the word כנגדו is that whenever one confronts someone of equal power, moral and ethical weight, such a confrontation is termed נגד. It is a head-on collision of will. When the two parties disagreeing are not of equal power, or moral/ethical weight, the confrontation is termed as one being עולה or יורד one of the adversaries either prevailing or losing in such an encounter. It is in this sense that we have to understand such statements as משה שקול כנגד כל ישראל, “that Moses was the equal of the entire Jewish people.” (Mechilta Yitro 1) However, the Torah did not mean for woman to be 100% equal to man, else how could the man expect her to perform household chores for him, etc.? Hence the letter כ at the beginning of the word כנגדו somewhat tones down this equality.