Eve goofed by talking to the serpent. Adam goofed by not correcting Eve's goof before it became a sin.
Eve didn't talk to the serpent. The serpent talked to Eve.
Adam didn't need to correct Eve. Adam needed to find something else to do.
If it had not been a husband/wife situation, Adam may not have been the one in authority over Eve.
Genesis 3:2,3:
So, even though Eve didn't sin by disobeying a directive from God in her speech with the serpent, she may have lied. Perhaps we don't have the whole conversation that God had with Adam and Eve. Perhaps God did indeed tell them to not touch the fruit. But we don't have record of it.
How did Eve know that disobeying God would be wrong before eating the fruit from the tree of knowledge of good and evil, only after which she would have known it was wrong?
God had told Adam and Eve before they ate the fruit, that the day in which they ate it they would surely die. We have no record of God saying at that point that it was wrong to select death. But here is how I look at it.
It is rather easy to destroy life. People do it all the time nowadays. But it is almost impossible to make life. Perhaps we are close to it in some ways.
Since God made the complexity that was Adam and Eve, and then breathed His spirit into them, the destruction of such complexity is wrong.
However, my thinking aside, there are others, in the Bible, who call it a sin in one way or another.
But Eve wouldn't have known that the destruction of such complexity is wrong. God didn't grant her this knowledge beforehand; He simply warned her not to eat it. She wouldn't have known a distinction between whether it was better to listen to the Serpent or to God. She could only know this after eating the fruit.