There are moments of bleakness scattered through out Gibson's Neuromancer which stops me in my tracks with their desolation. But as I tried to wrap my mind around the jungle of technology and threads of the plot, the overwhelming feeling of isolation is what lingers behind after I shut the pages of the book. There is an emptiness in the space in between characters, there is no sense of absolute faith, of trust, or of love.
Case is alone at the beginning of his journey. Linda Lee had meant a great deal once upon a time, but her betrayal left him unable or unwilling to trust anyone else. Even with Molly, who opens herself up with rare moments of vulnerability, Case is unable to have anything more than a physical relationship and a sense of wary, but mutual respect. Molly too, remembers a lover who meant something. But she is no longer able to enter intimacy with someone else. At the end of the book, after all that they had been through, molly and case are still alone. still isolated.
There are several possible reasons why isolation pervades in Gibson's futuristic universe. The characters' inability to form close relationships with one another could come from the blurring of the line between humans and machines. With self-aware AIs, humans who are physiologically composed of machinery (Molly), humans who are only alive through machines (Dixie), it becomes unclear at which point humanity begins and ends. If we are to believe that the part of us which is responsible for our "human" emotions such as love and compassion is dependent upon receiving "human" input, then as the cyborg becomes composed more and more of machine, the human input decreases and our need for intimacy atrophies. In summary, the lack of intimacy in Gibson's world is due to the fact that the characters are either no longer human, or on their way their. They are no longer capable of human emotions.
Another contribution to the lack of intimacy is the lack of a clearly defined truth in the Neuromancer universe. When Marley meets Zirek in Count Zero, it is really only an apparation that she sees. But because of the advances in technology, Marley's perceptions fool her into believing that he is real. When one is betrayed by their senses, anything, or anyone would be untrustworthy. In Neuromancer, the relationships between Case, Molly, Armitage, etc. are all filled with a sense of doubt, of guraded and shifting loyalties. In this futuristic world, it is every man out for himself - there is no one to rely on, there is no one to trust.
Through all the horrors of the matrix and other technologies, it is the void in the space in between that is the most frightening of all - to live a life of isolation.