Loneliness is the not feeling alone. One can feel lonely surrounded by people, with family or even when engaged in romantic relationships.
Loneliness for me is the feeling of being lost. Not belonging anywhere. Not being understood by anyone. Having no one to trust.
So, loneliness is not really something you can solve by just not being alone, trying to go out and meet people. It has to be solved by deliberate practice of understanding your needs and behavior.
What do you like doing? What do you need to do to feel emotionally satisfied? Initially all answers you might get would be related your desire to have other people around. But gradually as you try to understand why you have the desire to have those people around you, for you to feel satisfied, you will notice that it is because you do not fulfill that particular need yourself, that you expect others to help it fulfill it for you.
Allow me to share a personal example. Recently I went through a break-up. As expected I felt a surge of pain, pain of losing someone I truly cherish in my life. After some deliberation, I understood that I used to enjoy going out to different cafes in my city with them, which made me happy. Maybe it is their presence or it was the experience of sitting in a cafe, but something brought me that feeling of happiness.
Next weekend, I took myself to a cafe I had never visited. I ordered what I usually order: hot chocolate. And soon after it, I left. But this experience, brought out a thought that had helped me find my way: If there is something I like, I am capable enough to get it for myself. If I like going out to a cafe, I can go out to the cafe with myself. If there is a need of mine, I can fulfill it myself, even if partially for now.
I am interested in knowing what are you going through? Please write it to me on the email: feelinglonelyxyz@gmail.com