In my case, I just adjusted myself around different people.

I was never good at making small talks, was mostly too busy with my own life. I had friends and it's not like I didn't care for them, it's just that I didn't talk unless I had something to say, and that kind of came as selfish. I realised I was kind of isolated in my own circle of friends. They all did things together which I only came to know about later through their posts. And forget about talking to new people and become friends. I have no trouble in having a conversation, but somehow it never went to the friendship stage. I started with trying to be more likable. Kept a log of when I last hung out with my friends or just had a conversation with them. Started talking even when I had nothing to say, I would just ask about their life and stuff that interested them. This part was very boring for me because I exactly knew what all was going in their life, which was not much, just like my life, but god do people like talking about their life. Also, for new people made up a grand set of crude jokes, witty remarks and fun trivia and all that. The result was that not only I made many new friends, but I felt more included in stuff now.

The downside was all the effort I had to put. But I guess it's better than feeling lonely.