I totally agree with it. But the Fai/Tomo thing...oh no, please not! Even if they maybe were a funny pairing...xD
I didn't mean it as a pairing ^^;. But them team up against Kurogane? I can see that very clearly

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And about Tomoyo - she does love Kurogane, but as a brother or a dear childhood friend. Not in a romantic way. In every world, in every dimension, Sakura will always be her most important person - even if she hasn't met her yet. It's an unrequited love, but as CLAMP said, it's the ultimate form of love, to love a person and want them happy, even if it doesn't necessarily mean your own happiness. It's even clearer in Tsubasa now, that a person's true love, stays a true love, no matter what AU version of a character it is. I mean, look at Syaoran and Sakura - CLAMP killed C!Syao and C!Saku just that they could be together. Is it the first time, CLAMP have done something like this? Nope. It's not the last time either.
Please, if anyone could point me to one scene, in which Tomoyo blushed around Kurogane, then I might consider this pairing being romantic. But even in CCS, she looked fondly and wisely at all her friends, and that's exactly, what she's doing in TRC. She's like that, she's very mature for her age, and she can clearly sense the feelings of others, as Eriol pointed out in CCS. If Kurogane loved her, she would know. But what she's done so far, contradicts the possibility of her feelings for him being romantic. Tomyo, for starters, is the one, who sends him away, to find a meaning of true strengh. While this like ShirubiaLamperouge said probably isn't something you can teach easily, it's something you can never discover alone.
So, how does he find it? In sacrificing himself for Fay. And then, it's Tomoyo, who tells him "If you want him to go with you, if you wish for it with all your heart...". That's not something a person in love says about their potential "rival".
It's just that they haven't shown any kind of romantic inclinations towards each other. They act like friends, not at all like how touya and yukito acted together, for example.
Not every CLAMP shounen ai/shoujo ai pair acts like Touya and Yukito. It's mostly the opposite. Subaru and Seishirou were trying to kill each other numerous times. Taishakuten killed Ashura-ou, because his lover wished for that. Kazahaya and Rikuo are bickering like an old married couple, while Saiga and Kakei are definitely not just hugging all the time. Kendappa killed Souma, and then herself with Souma's weapon. Saya died for Tohru. All of them never kissed, but all of them are canon (well, maybe Kazahaya and Rikuo aren't, yet). In CLAMP, it's not really about words, but actions. What Kurogane and Fay have done for each other is more than Touya and Yukito ever could. I'm positive, Kurogane and Fay never slept together, but their bond is that of soulmates, which in CLAMP equals romantic love.
It doesn't seem like anything more than another ship from yaoi loving fangirls who will leap on anything at all and turn it into a couple.
Oh, to the contrary. While there is a vocal group of yaoi loving fan
brats, this ship has fair amount of fans, that never ever liked anything shounen ai-ish in their lives before. One of my closest friends despised yaoi, until she read TRC, and fell in love with Kurogane/Fay. And there's, of course, fans that just love a good chemistry of two characters, no matter what gender they are.
"besides, no matter where you are, I always know. You, and only you." thing, and the vow, and the secret name that only she knows, AND the promise to return, and then when she says how he truly understands the meaning of true strength and lays her hand on his shoulder and gazes up at him adoringly.
They have a strong bond, there's no denying that. But that doesn't necessarily mean a romantic bond.
The vow was a formal oath, recited by a servant to his master. Generations before have said the same words, and I don't believe, all of the ninjas were in love with their masters.
The meaning of true strenght, is something Kurogane understands because of Fay, and Tomoyo knows it. She's happy, Kurogane's finally grown up, and found his peace. She kinda does look the same way at Fay, if you pay a closer attention.
Kinda long post, but one last thing: I would totally ship Tomoyo with Kurogane. They have all the things I like me in a pairing. But Tomoyo's love for Sakura, is something so beautiful and inspiring, that I can't simply ignore it. I adore Tomoyo too much for disrespecting that part of her. I could see Kurogane having a crush on her, while they were little, but never anything from Tomoyo.
I didn't even consider Kurogane and Fay as possible soulmates until Tokyo, but then all the tension, all the looks, and all their actions spoke louder to me, than any love confessions.