[Dark Night of the Soul] can occur at any point in one’s life, but it usually emerges after a spiritual seeker has attained a lot of spiritual knowledge or growth. This is because the ego is now being called out for what it is and it tightens its grips on you to hide you from the light that you are.
Even though this is a very beautiful and sacred process, it can be perceived at the time as very difficult. Especially when you are in the thick of the fog. This is why it is called the dark night of the soul (it may feel like a dark century of the soul to some).
You feel as if you are stuck in the dark with no hope of seeing the light again. You already feel totally alone due to this process, and on top of that it is not talked about often in spiritual texts. This is because a lot of us look for the light only and try to run away from the dark, not realizing that the dark will only grow larger the more you ignore it.
Read the full article by Tathina, here.