They are'nt in love, they're just friends n__n don't worry about that xDD
Ahem. Have you read the manga, Luci-chan?
*Before going abroad, Mizuki-sensei tells Touya that when the two of them will meet again, they will both be in love with someone else. Mizuki fell in love with Eriol. Now do we ever see Touya being lovey-dovey with anyone else but Yukito?
*When Sakura told Yukito she was in love with him, he let her down, and told her that he wasn't the one she really loved. She asked if he could tell because he himself had a most beloved person, and he said yes. She asked if that person was her big brother, and he admitted it was.
*Yukito asks Touya at one point why he doesn't mind him being around Sakura, to which Touya replies with going all sparkly sparkly (I'll see if I can find the actual scene, but you all know what I mean by "sparkly", right?), touches his cheek and starts saying "You are...", but then they're interupted.
*Only occurs in the anime, but a girl tells Touya that she loves him. He lets her down, saying that he already is in love with someone else. She answers that she kind of knew he was.
But if you want to be in denial, fine... ^^