The following comes directly from the LDS Old Testament Institute manual in regards to Genesis chapter 3.
Elder James E. Talmage explained how, even in her being deceived, Eve still brought about the purposes of the Lord:
“Eve was fulfilling the foreseen purposes of God by the part she took in the great drama of the fall; yet she did not partake of the forbidden fruit with that object in view, but with intent to act contrary to the divine command, being deceived by the sophistries of Satan, who also, for that matter, furthered the purposes of the Creator by tempting Eve; yet his design was to thwart the Lord’s plan. We are definitely told that ‘he knew not the mind of God, wherefore he sought to destroy the world’ [Moses 4:6]. Yet his diabolical effort, far from being the initiatory step toward destruction, contributed to the plan of man’s eternal progression. Adam’s part in the great event was essentially different from that of his wife; he was not deceived; on the contrary he deliberately decided to do as Eve desired, that he might carry out the purposes of his Maker with respect to the race of men, whose first patriarch he was ordained to be.” (Articles of Faith, pp. 69–70.)
Eve was innocent, and her pure naivety is what left her susceptible to Satan's deceit. Because she had not yet partaken of the fruit, she did not have the knowledge of good and evil. She did not know Lucifer for who he was until after partaking of the fruit.
We should look down upon Eve for being deceived. She did not know any better. She was trusting and innocent, like a small child. She did not know right from wrong. Satan's efforts to frustrate the plan merely enabled it. Father knew that in her state of innocence, Eve would yield to the enticings of Satan. He designed the plan this way. It had to be.
Eve was beguiled.