loneliness is an emotional state that occurs when a person feels disconnected from society, even being among people. It's not just the absence of other people around, but a feeling of inner isolation. this can be caused by various reasons, from social isolation to internal imbalance, which, in turn, consists of traumatic experiences, internal attitudes, mental exhaustion, etc.
loneliness can also be a signal that contact with one's own feelings and desires has been interrupted. a person cannot, is afraid, or simply has no right to hear their true desires, emotions, and needs, and thus isolates themselves from the world. as if he was losing hope of getting what he needed from the world.