2 Nephi 5

As Nephi continued to admonish his brothers to keep the commandments of the Lord, they finally reached the point were they didn't want to hear it any more, in fact as does all the wicked they blame their temporal conditions on others saying -

"..we have had much trial because of him; wherefore, now let us slay him, that we may not be afflicted more because of his words. For behold, we will not have him to be our ruler..." (Book of Mormon | 2 Nephi 5:3)

It's seems because of pride we tend to blame others for our failures. Nephi also provides an example that there becomes a point that it is necessary to leave those that we are striving to help when we are in physical or spiritual danger for Nephi writes -

"...that the Lord did warn me, that I, Nephi, should depart from them and flee into the wilderness, and all those who would go with me." (Book of Mormon | 2 Nephi 5:5)

I believe the Holy Ghost will also warn us when we are in spiritual danger to leave to situation or condition we are in.

One more thought. Throughout the Book of Mormon the prophets used the word "curse" where the Lord would curse an individual or group. I believe this so called curse is not as many in the world would see a one destined to bad fortune. I see is as a stoppage in ones eternal progression. In my mind, this would be a curse, to not allow one to continue to grow until one repents where the curse would be lifted. Nephi writes of his brethren of whom he fleed -

"...the word of the Lord was fulfilled which he spake unto me, saying that: Inasmuch as they will not hearken unto thy words they shall be cut off from the presence of the Lord. And behold, they were cut off from his presence.
21 And he had caused the cursing to come upon them, yea, even a sore cursing, because of their iniquity. For behold, they had hardened their hearts against him, that they had become like unto a flint..." (Book of Mormon | 2 Nephi 5:20 - 21)

In my mind, this was the curse, that they were cut off. Their progression had ceased because of the inquities, hardening of their hearts as flint. Flint is hard and unyeilding, even in spiritual things. It was then that Nephi writes -

"...wherefore, as they were white, and exceedingly fair and delightsome, that they might not be enticing unto my people the Lord God did cause a skin of blackness to come upon them." (Book of Mormon | 2 Nephi 5:21)

Note that the darkness of the skin was not a curse. It's purpose was as signe so Nephi's people would avoid those that would influence and destroy their eternal happiness. It was a sign.