The old, self-indulgent liberal query (at least when out of office): Why can't we all get along? Answer: Because people have different ideas about their preferred reality, which are sometimes incompatible. And no friendly smiles or reasoned discourse can change that.
Generally, when nations have sufficient reasons to come to terms, they will do so. It's not lack of dialogue or 'misunderstandings' of each others natures, which prevent peaceful coexistence. The sources of mutual hostility are found in what Marxists call 'objective factors'. When those objective factors change, or the weight assigned to them by the antagonists alters, then previously insuperable obstacles of mutual 'misunderstanding' can dissolve surprisingly quickly.
Mao Zedong spent half his life denouncing America. No channels of communication of any kind existed between his government and the US. Yet, when relations between China and the Soviet Union deteriorated, and he needed a powerful ally, that history of enmity counted for nothing, no more than rhetoric or ideology, and the word went out, and found its way to the ears of Henry Kissinger, who was soon on a plane, and shortly after that Richard Nixon, the old communist baiter, was walking the Great Wall, and a pure, new friendship was born.