to be able to improve your relationships with others you might need to reach an acceptance and learn how to enjoy time alone. I have almost always struggled with codependency issues and am just starting to learn how to be alone and not have the deep desperate feelings that I have had most of my life. if you think you may have codependency issues you should look into cbt, I have found it very helpful to manage emotions.
Sorry to hear how you feel - I was (and to an extent still am) in the same position. I think what helped me is to join "groups" of people where interaction is more natural - for me, it was getting an internship (interaction with colleagues) and joining extracurricular groups (e.g. Eco Team). Even if it's a purely functional relationship that's based on getting advice from someone more senior. There's also a group called London Shyness Social Group (or something similar to that name) if you want to interact with others who want help with their social ability - you'll all be on a level playing field that way!x
I accepted being lonely for a long time. I don't mind my own company, I like my solitude, and at least I know what I'm going to get from myself. However, after awhile, the loneliness becomes overwhelming and the desperation to just have a friend is almost suffocating. So to an extent we should be able to be lonely and not feel as if it's entirely a negative thing, but on the other hand we should not have to be constantly lonely to the point where it may never change.