PofGP 3

In contrast to the Genesis record, the Lord said to Adam -

"...I, the Lord God, commanded the man, saying: Of every tree of the garden thou mayest freely eat,
17 But of the tree of the knowledge of good and evil, thou shalt not eat of it, nevertheless, thou mayest choose for thyself, for it is given unto thee; but, remember that I forbid it, for in the day thou eatest thereof thou shalt surely die."  (Pearl of Great Price | Moses 3:16 - 17)

Of this, Joseph Fielding Smith explained -

“Just why the Lord would say to Adam that he forbade him to partake of the fruit of that tree is not made clear in the Bible account, but in the original as it comes to us in the Book of Moses it is made definitely clear. It is that the Lord said to Adam that if he wished to remain as he was in the garden, then he was not to eat the fruit, but if he desired to eat it and partake of death, he was at liberty to do so. So really it was not in the true sense a transgression of a divine commandment. Adam made the wise decision, in fact the only decision he could make” (Answers to Gospel Questions, Vol. 4, page 81).

We have no idea how long Adam and Eve lived in the garden.  It seems to me that Eve eventually longed for more and chose to eat of the fruit and not remain in the garden