I believe that loneliness stems from something missing–some big void in someone’s life. That could be the spouse, or it could be an unfulfilling life, which can include being unhappy at work or not having a hobby, an outlet or a passion that is satisfying.
Loneliness is hardly seen as a serious disorder, but in reality, chronic loneliness and feelings of alienation can be extremely detrimental to health. It can induce alcoholism, make a person suicidal and increase the risk of mental health disorders.
Loneliness often goes hand in hand with one major health problem — depression. In fact, the American Psychological Association says that loneliness is a specific risk factor for the mental health condition.