A shy man means a lonely man—a man cut off from all companionship, all sociability.
 Jerome K. Jerome, Idle Thoughts of an Idle Fellow (1886). copy citation

Context

“These and the rest of a shy man's troubles are always very amusing to other people, and have afforded material for comic writing from time immemorial. But if we look a little deeper we shall find there is a pathetic, one might almost say a tragic, side to the picture. A shy man means a lonely man—a man cut off from all companionship, all sociability. He moves about the world, but does not mix with it. Between him and his fellow-men there runs ever an impassable barrier—a strong, invisible wall that, trying in vain to scale, he but bruises himself against.” source