Dearest Twilight Sparkle,
My most faithful student, your naivete is remarkable.
False friends may exist, but even they can have true friendships until something happens that forces the issue. Until then, that friendship is impossible to differentiate from a true one. This is why I question your friendships and their hasty formation.
Granted, such friends may not treat your other friends too well. But friends of friends don't have to be friends, and that's why everyone has social circles. If I tried introducing some hoity-toity nobles to Cuppa Joe down at his rustic cafe, how do you think they would react?
They nitpicked his beans, so he pissed in their coffee. They praised its salty, earthy flavors as he served me chamomile tea.
I love that guy. Should introduce Luna to him sometime.
So there you go. If you know your friend's a callous witch, it's a good idea to not bring them around anything that will irritate them.
Like Pinkie.
Love,
Princess Celestia
Luna, want to go out for coffee?
Yes, I promise it's decaf... and won't have milk or sugar in it.
Fine! Luna, I solemnly state that I will not mess with your coffee the entire time we’re there.