Stu has no friends except his brother. He would desperately love to date women, but he is certain no woman would be interested in him. Stu won't get involved in friendships unless he's a hundred percent certain the other person likes him. Stu often turns down opportunities to get ahead at work when they involve interacting with others for he is terribly afraid of criticism. He tried a dating service but was convinced that the secretary was trying to get rid of him because he was such a poor candidate. The most likely diagnosis for Stu is