Dear Twilight Sparkle.
I am indeed renting out that private tower of mine. Not to you, of course, but to ponies who can appreciate my leadership. Fortunately, it appears that Rarity does, so I shall make sure she's comfortable. And maybe at the end she'll realize just how much better life in Canterlot is.
As for you, why would you ever rely on her? You know that her dresses are no use in getting you laid! I mean, just look at how you didn't get any at the Grand Galloping Gala! (Admittedly, that may or may not have had something to do with the unfortunate events of the night, which I feel we've probably discussed already.)
Of course, it really boggles my mind that you would be so rude as to interrupt her vacation, especially if her cat is sick. I mean, clearly her pussy is quite tender at the moment and needs to be cared for properly. Then again, if it means you'll get an unsatisfying dress out of it, then why not.
Still, kudos for Rarity for keeping up with both you and the Canterlot Elite at the same time. She really should have just ditched you at the first chance, but she persevered and managed to keep the proletariat from noticing anything wrong. Even if it did result in her missing out on the part where you all had fun licking cake off of Rainbow's body.
Overall, I am very pleased with Rarity's developing Unicorn-ness. Clearly she has realized that her destiny is to be part of the second greatest race in the universe. (Alicorns such as myself are the greatest, of course.)
Your eternally superior ruler, Princess Celestia.
P.S.: Why do you think he Fancy Pants doesn't actually wear pants, hmm?