Being around gentle people always made one happy, so... between Setsura and Yōki, Nura Nurarihyon in the original story had directly given up Setsura, who had loved him for a hundred years, and fallen in love with Yōki after meeting her only a few times.
Setsura seemed to exist solely to highlight Yōki's warmth and cuteness.
That was extremely unfair to Setsura.
Setsura had fallen for Nura Nurarihyon the first time she saw him. Back then, Nura Nurarihyon had not yet formed the Nura Clan and was still alone.
While he was out in the wilderness, Setsura had begun helping Nura. Even when he left, she had followed Nura Nurarihyon without the slightest hesitation or regret.
Then she helped him establish the Nura Clan and meticulously managed everything.
But none of that truly mattered to Setsura. She simply kept giving for Nura Nurarihyon's sake. Yet in the end, after loving Nura Nurarihyon for five hundred years, she had... gained nothing.
In the original story, after Yōki died, she even helped Yōki look after young Rihan...
Although she had a daughter, that daughter had actually split off from her. Yukina did not need men to produce offspring.
So how could someone who loved Nura Nurarihyon be allowed to suffer for hundreds of years?! She had done so much for Nura Nurarihyon, and for centuries, he had been the only one in her heart, yet she had gained nothing in the end...
How could that be her ending?
Therefore, Nura Nurarihyon and Yōki could not be together. It was better to bring Setsura and Nura Nurarihyon together! They were the perfect match. After all, Yōki was human and only had a few decades to live, while Nura Nurarihyon could live for a thousand years as long as Hagoromo Gitsune did not