When I was in secondary school, my English teacher taught me the difference between the word “alone” and “lonely”.
Alone is a physical state, where you are all by yourself physically. Nobody else is around you. For example, you are alone in your room. You are literally by yourself. Being alone is not an issue.
Lonely is an emotional state, where you feel like you are alone even though there are other people around you. You somehow feel isolated in your own world and you feel like nobody is there to share your experience. You can be lonely in a crowded room. Loneliness is an issue.
If you are lonely, try to reach out and open a little bit of a room for someone to enter your world. I know, it is easier said than done.
But you might surprise yourself by having someone else who is experiencing something similar to what you are experiencing. Maybe you are not the only one in the world with that problem.
Knowing that doesn’t make the problem go away, but it does remove the feeling of loneliness. If anything, that is a good first step towards healing.