She was offered a marriage to him when they first met. During the fight for the throne, she developed what she thought was a sincere relationship, but it was slowly worn away by the harem battles. After being reunited, she was no longer a young girl and no longer naively thought about a couple, but she didn't expect him to leave early. It was only when she reached the end of her life many years later that she truly understood that love lasts forever.
(A fictional era, but still borrowing from the Qing Dynasty system)