User blog comment:Twilight Despair 5/New Plots/@comment-3169324-20180523192047/@comment-3423279-20180523195643

Perhaps because her nature also includes the Nothingness and it was tipping into her full nature? Light being removed would mean darkness spreads, but Beings removal would cause Nothingness to similarly exert itself.

Without that Being aspect to balance out the Nothingness aspect, Amara's Darkness would be swallowed up by her Nothingness and everything would cease to be.