How to deepen friendships when it's really hard?

I have always ahd trouble formingg frienships. Ever since I was born, I couldn't keep and maintain frienships. I have had a close friend but then she moved to another country. I also had social phobia but now my condition is improving and I feel much happier. I have formed some basic frienships but I feel like I am repelling the need to get much closer to my friends. I don't know why I have that feeling. But I feel lonely and at the same time I don't want to. So the result is my friends become more closer to each other and I am not. So what can I do to become better?

You just have to let it grow stronger and eventually if its means to be a deep relationship it will be one