You asked a very good question, and it is something that I feel as well. You are not alone in your thinking, there are many people who feel similar to you. Do not feel ashamed for feeling the way that you feel. I think everyone who has responded has given you amazing answers, and your words along with the responses from everyone made me tear up. I think the fear of being "alone" is very real for many people, at some point in life. Some people can be surrounded by the best family members and dozens of friends who all love them, but that person can still feel alone or lonely. I can relate to that feeling. I think talking professionally to someone can help, along with making yourself realize how you can be just fine loving yourself and on your own. But I get it, it is a constant struggle. What I will say for you not to do, from my own personal experience, is get into random relationships with people if you recognize it is not the right fit for you. It will only make things worse. I have learned that it is better to be alone, than to be surrounded by the wrong company. Although I feel very lonely often, I would rather feel this way than be with the wrong person. How I look at it, is if someone does not match my efforts, bring what I am bringing to the table, and does not better me as a person...I don't need them because I already got myself, so what's the point if there is nothing of value to be added to me or my life? I am not simply going to add someone into the mix, just to say that I have someone. That is foolishness.
What has helped me is that I have been trying to focus on myself and my goals for life, new careers, and new opportunities to meet new people. Music helps me escape, as does going out with family and friends. Laughter is the best medicine, and I laugh at everything. I am a true believer in the saying, "A day without laughter, is a day wasted." It truly is a waste. No matter how upset or sad I am, I always find a reason to laugh or smile...and there IS always a reason :)
Another thing that has helped me is to adjust my way of thinking. Rather than focus on the negatives and everything that I feel is wrong in my life, I try to look at the positives and everything right. Things will eventually fall into place, it is a matter of having patience.