I share your need for solitude, but I don't consider it an anxiety or phobia. And you shouldn't either.
Some of us were just meant to be alone. If you learn to love solitude, as I have, then what seems like a curse, becomes a blessing. I am perfectly content with my own company. The only time I ever feel uncomfortable is when I'm with people who are full of negative-energy. Then I get "lonely" for my solitude! And when I get back into my own space, I thank my guardian angels for getting me home.
I never feel lonesome. I never look out the window wistfully, and think that Life is going on somewhere -- and that I've been excluded. Never!
For most Americans, the two most frightening words in the language are "home alone." To be home alone, without TV, computer, cell-phpne, radio, etc, is most people's worst nightmare. They'll do ANYTHING to prevent being left alone with their own thoughts -- including mindless driving just to kill time.
To my mind, Jawg, you are completely sane. It's your relatives and friends that are caught up in the soap-opera of life, who are loony. I am NOT saying that everyone should live alone! But I AM saying that if you're solitary by nature, as you seem to be, don't consider it a defect which you have to overcome.
Have you read any GOOD books about spirituality, Jawg? Authors like Eckhart Tolle, Swami Rami, Anthony De Mello, Joan Borysenko, and others? If not, you might want to consider it.
Once you become truly contented with yourself and your life, you'll find that other people will notice that positive energy, and want to be with you. At that point, you'll have the best of both worlds: lots of time to yourself, and, if you choose it, quality time with ONE person who resonates with you in all the important ways.