http://www.huffingtonpost.com/johann...b_6506936.html
The Ring caused Gollum's isolation because he wanted it more than he wanted anything else. Being with Frodo and Samwise brought human contact into Gollum's life, and began to ameliorate his addiction. It was Samwise spoiling that human connection that sent Gollum back into the slavery of his addiction to the Ring.
Tolkien intuitively knew something very important about addictive behavior and the hooks involved, that we're still only beginning to really understand.