Sorry it's so short; I only own Moriko. Hope you like the ending (not of the whole story though, even if this is the final letter)
August 3, 1895; Human Realm
Hiei,
I would like to tell you that I have not yet received the reply you probably sent to me in response to the letter I wrote on July 30. In fact, since it has only been four days, you probably have not even received it as I write this letter.
However, all that is beside the point. I write to tell you of a matter of the utmost importance. It is about my brother's partner, whose name I shall not reveal in order to maintain his safety. He has decided he will no longer work with my brother.
It is very hard to write this, but I must. He will be staying with me, Hiei. I love him. I am so very sorry. I understand your feelings for me, but I can no longer honestly return them. So, farewell, Hiei, and may your life bring you happiness.
Your apologetic forest child,
Moriko
Each of the two friends read the letter silence. When they reached the end, the world stopped. They both pained for the loss Hiei received a hundred years previously. Yusuke because he finally understood Hiei a little bit better; Kurama, because it was indirectly his fault.
Finally Kurama said, "And she said I was cruel. She tells him she loves him, addressing the letter dearest Hiei. Then four days later, addresses the letter Hiei, and tells him she loves another man."
Yusuke was quiet for a moment. "…So this is the reason Hiei always seems so distant, so cold… so hateful. He's afraid. Afraid of being hurt like that again."
"Yes. It's disturbing, isn't it? Days ago I wouldn't have been able to comprehend the idea… but now it seems so obvious. I keep asking myself, 'How did I miss this?' And I think the answer is that I wanted to miss it, and I saw what I wanted to see."
"I have… you'd probably use a word like preposition but I don't even know what that means, so I'll say idea. I have an idea."
"Yusuke, the word you meant was proposition."
"Whatever. Anyway, you said Moriko is still alive, right?"
Uneasy and unsure if he should even answer, Kurama replied, "As far as I know, she is."
Kurama's eyes widened in shock at Yusuke's next statement: "Then let's go see her."