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.

That said, if you are 14, then you might have difficulties engaging with those texts. But also, if you are 14, you should not get too deep into existentialist philosophy. You'll be even more outcasted.