The lack of a Tyrell POV is a real shame!
Good point, Rapsie. Simply too much game-playing was going around, and when the fall out happened, the Tyrells retreated to their corner and left Sansa to deal with the mess. This is one of the reasons why I can never really support the Willas match, although Sansa at least made a conscious choice to go there and be happy. She was just another pawn in that particular game. Perhaps a more enlightened pawn, but still a pawn. Sansa's development into a player necessitated that plot falling through.
I can only imagine the possibilities of the trouble the two of them could have caused for Tywin and Cersei if they stayed cool and played the game, it would have been epic to watch as their game unfolded (I for one would rather be learing the game from Tyrion that LF, because at least I know where I stand with Tyrion) but it was not to be.
I await your response then, TTH Just to be clear though: there was never a possibility of Tyrion and Sansa working together to cause trouble for Cersei and Tywin. While Tyrion might not have any love for his sister and father, he's still dependent on them for his livelihood. And his entire desire to get away from them meant going along with Tywin's plans (somewhat unknowingly) for the Red Wedding and marrying and bedding Sansa. Sansa hates Lannisters, and Tyrion is a Lannister. During the first three books Tyrion's loyalty, however grudgeful, was to his family. Now that he's fallen out with them, his loyalty is to himself. He remains a wholly unsuitable ally for Sansa.