Humans are animals, so guess what? They have a need to belong to someone, too. Whether we call this family, friends or something else, we have this basic need to belong to a group and feel like we should be there. We want to be included. We need to feel loved and wanted.
What happens when we don't? It has already been established that we are not meant to be solitary beings. Although, there is a distinct difference between alone and lonely, they often feel very similar. One can be alone and not be lonely - but this is usually only true in temporary situations. Alone is not meant to be permanent. One can also be lonely and not be alone. It comes from missing out on that sense of "belonging". There are words for it, like "wallflower" and "outsider". Most people who feel like that lonely outsider would give just about anything to gain that feeling of belonging. But how do you gain that feeling?
It is one thing that cannot be gained by the person who needs it the most. It has to be given freely by someone else. If not, that feeling is tainted and cannot be trusted to be real. A person can try to belong and can reach out all they want to find a connection, but it is only real if the other side reaches back. It cannot be one way and be real.
So, if it is a basic instinct and it cannot be gained..... how does a person make that connection happen?