Why Yami/Tea?

Personality Balance

Well, I admit, this couple is a bit more of a reach than Yugi/Tea; after all, they do not end up together in the anime. But then again, its bittersweet romance and latent potential cannot be missed, even in the dubbed version of the show. Sure, Yami's a 5,000-year-old pharaoh (or, if you're a fan of the original, 3,000), and sure, nobody has seen that Tea even has an Egyptian past...but to me, they also seem to balance each other. Though some would say their personalities clash horribly, I believe that their spirits balance out, with Tea's more lighthearted nature helping brighten Yami's more serious personality, and Yami's quiet drive underlining Tea's bright ambition.

Life Stages

Yami and Tea are both at emergent stages of their lives. She is on the brink of realizing her dancing dreams; he, too, is on the brink of realizing his destiny. Since both of them are transforming, they find a sort of kinship with each other during most of the anime. Shared experiences are a powerful way to transform one's feelings about another person, and even though there was obvious romantic tension between them in the anime, it was not realized, because in the end, he transformed completely and realized his destiny before she did. Therefore, just as she could not follow him into the afterlife, she could not follow him into the next stage of his life, even if he had stayed in the same plane of existence.

Other Theories

I also like to think that Yami is more afraid of the future and what it might bring, and that's why he may appear disinterested in Tea during some of the series. He may be afraid to hurt her by loving her, knowing that at any moment he could be taken from this world if he loses a duel. Part of Tea's purpose, I think, is to help both Yami and Yugi realize faith in themselves to be able to win and faith in the "powers that be" to guide them through life and protect them even as they are valiantly protecting themselves.