Syaoran and Yukito
In the entire first and second season Syaoran has a big crush on Yukito, however in season three he has a little confrontation with Yue (episode 51) Where Yue tells Syaoran that he only thought he loved him because he was attracted by the powers surpressed inside of Yukito (so in short he was attracted by his power).  But its still pretty funny to watch the anime and see Syaoran run away with a big red face whenever he is around Yukito.  (Also in the third season Syaoran starts blushing less and less and doesn't even really think too much about Yukito because of his growing love for sakura.