This is my favorite screen cap from the song.

Loooook at those bed room eyes! Look at them! Look at them! That raised eyebrow! Look at that dork!

And the fact that Rarity took the book away and pulled her into a hug. Squee!

Come to think of it, Rarity and Twilight have quite a few moments (i.e. gazing into each other's eyes) that seem just a bit more than mere friendship. I'm not trying to use it to outright prove Raritwi is OTP, but I'm just saying...