As I understand it, The Rav feels lonely, as a man of faith he feels definitionally lonely because he can't relate to people and people can't relate to him. Why doesn't he find solace with G-d though? He himself says, referring to G-d, "the teacher is inseparable from his pupils, and the shepherd never leaves his flock". Shouldn't the infinite G-d be able to relate to him, and him being an Adam 2, a man of faith, relate to G-d?
[W]e must distinguish between being alone and being lonely. Aloneness means lacking love and friendship; this is an entirely destructive feeling. Loneliness, on the other hand, is an awareness of one’s uniqueness, and to be unique often means to be misunderstood. A lonely person, while surrounded by friends, feels that his unique and incommunicable experiences separate him from them. This fills him with a gnawing sense of the seemingly insurmountable gap that prevents true communion between individuals. While painful, this experience can also be “stimulating” and “cathartic,” since it “presses everything in me into the service of God,” the Lonely One, who truly understands the lonely individual.
Thus, he feels lonely in the sense of a feeling of uniqueness and separation from other people. A relationship with G-d is not going to change those feelings.