How can I be sure I am lonely?

You can be sure you are lonely when you distance yourself from other people. And what I mean by this is that you are not surrounding yourself with others or you just don't enjoy being around the individuals close to you. Also when the people around you don't communicate or reach out to you: in the sense that are people you know but still they do not open up a conversation with you. You can also be sure you are lonely when you stay by yourself a lot. Whether it's when you are at home or school.

Sometimes people feel "alone in a crowd". This could possibly indicate that the person doesn't feel that they can be 'themselves'? It could also be a feeling when certain desires, expectations, goals, or just a general outlook on life is not shared amongst your peers? The notion of being lonely can also be a ramification of feeling that no one will understand how I feel about this or that. The idea that no one around can identify with me? People can have a lot of friends and still be lonely if something is 'missing' from their life? Loneliness can be conceived when everyone around a person seems happy and having a good time, but you are not?