Movies and TV shows are naturally biased towards social relationships and friendships because it's hard to present a first person point of view. Yet I assume that's where the future of entertainment lies, in first person virtual reality. Peep Show with David Mitchell and Robert Webb is the only exception I can recall but the humour there is fairly dark and nihilistic so it's hardly an endorsement for solitude (besides, they're flatmates). A counterexample from literature I can recall is Robinson Crusoe, who is alone on the island for the first time in his life but not lonely because of a new-found relationship with God.