Being socially isolated can be a serious cause of loneliness, this feeling can be normal in nature, but thus it likely stems from a situation, thought, feeling, excessive consumption of a particular void or inability to participate in some thing, which could be anything that can easily trigger loneliness.

This is not a condemnation on oneself, but if left on aired or attended to can lead to a large selection of depression, anxiety, fear and complex human emotion. So if you'd ask me I will say it's loneliness its self rather than the lack of a sense of community. These mood or feeling can come almost out of nothing.
My opinion.