Is there a solution to this problem or is this a part of the turbulent early 20's life?
Yes, sometimes it is hard when friends and family go on to live their own life.
You must start somewhere. Just by showing up, you take the first steps in the right direction to alleviate your loneliness. Be a yes person instead of a no person. When you get invited out to places or just when an opportunity comes your way, don’t be afraid to say yes. Just go for it and see where the adventure takes you. You never know where it could lead. Be completely honest about why you feel lonely and how you got there. It will help you fix the problem so much faster.
You can’t make new friends and meet new people by sitting holed up in your house alone. By forcing yourself to go out to social events, you increase your chances of meeting likeminded people who you get on with. Even if the idea of it seems scary and nerve-wracking, the more you put yourself in these situations, the more you will get used to them and the easier they become.
There’s a bigger picture here, beyond friendship: You have to cultivate an interior life that you enjoy.