Twelve may not be polite according to British standards, but brutal honesty is its own kind of politeness. I love it. This scene is really fucking important and, although I’ve got nothing against the Doctor/Clara ship (or any other ship, for that matter), I’m so happy the Doctor finally said it and that they’re both fine with it. And the fact that he mockingly, but gently, refers to Eleven as her “boyfriend” a moment later cements how self-aware and direct Twelve can be, and how much he values honest communication. … For now.
Basically so far, this is a Doctor who would go “by the way, Lucie, your auntie Pat was a Zygon warlord all along, are we alright?” and I have a feeling it’s going to drastically change the show in all sorts of wonderful ways.