You could read existentialist philosophy, which would give you a new perspective on loneliness. Loneliness is what 50% of existentialist philosophy is. My favorites are Nietzsche's "Thus Spoke Zarathustra" and "Beyond Good and Evil" and Satre's "Existentialism & Humanism". Gao Xin Jiang's "Soul Mountain" is really good too, Nobel Prize winning book. Or actually, also watch Ingmar Bergman's "Wild Strawberries" if you want to see a great film instead. .