Loneliness

Most people feel lonely at some point during their lives. We tend to be lonelier when young and also when old. Loneliness is subjective, one can feel lonely even when surrounded by many companions and someone can still feel contended even when being alone. “A teenage girl may feel lonely if she has only two good friends, whereas an 80-year-old woman may feel very connected because she still has two good friends,” by researchers Maike Luhmann and Louise C. Hawkley.
According to one research review, until age seven, young children are mostly looking for someone to play and have fun with. Then, it becomes important to have a close friend, someone you can talk to who is on your side. Peer groups soar in importance in the early teen years, when belonging and being accepted feel critical. As we head into our 20s, our needs for intimacy grow, including the validation and understanding that close friends can provide.
People with lower income are lonelier in middle age than people with higher income, more so than in young or old adulthood. People who are struggling financially can feel ashamed of their means, while everyone around them seems to be comfortably successful.
Loneliness also seems to spike when we develop health problems before our time. This creates a difference from others and thus contribute to our loneliness. Whereas someone having a health issue in old age is completely normal and doesn't feel different from the social group.
What’s the best response to loneliness?
Loneliness is more about our state of mind. Rather than focusing on how people are not there for us, perhaps we can be there for someone else. Joining a class automatically exposes us to a group of people who share at least one of our interests. It can also provide a sense of belonging that comes with being part of a group. Becoming a volunteer for a cause we believe  in can provide the same benefits as taking a class. We can always get a pet or say strengthening our existing bonds will also help.
Loneliness if not taken seriously might cause mental illness and if signs are prominent, it's best to consult a doctor. Remember it's never too late and nothing is more costlier than our mental peace.