勇者パーティーにいる婚約者に浮気されてたSランク冒険者、傷心を癒す旅に出る〜最強サレ冒険者はハーレムパーティーを作らされる〜 (Associated Names)

His beloved fiancée was summoned to join the Hero’s party, and they were separated. For three years, he desperately supported the Hero’s party from afar, eventually becoming an S-rank adventurer. However, when they finally reunited, his fiancée had been unfaithful—with the Hero. “Things turned out like this, and I couldn’t even repay my gratitude… At…