It stings a little, when Rose snaps that they're not friends. It's hard to dislike your boyfriend's sister, even if her mere existence did make Terezi feel a little superfluous. They weren't bosom chums or anything, but Terezi at least considered them passive friends. This Rose clearly had other ideas, but she wasn't going to let that sway her. They were still friends. End of story.

"Suit yourself. I'm still not going to fight you." Terezi smells when Dave steps to the side. She wants to give him some sort of reassuring gesture, but she doesn't know if that might set his sister off again. She settles for leaning forward just a little and bumping her shoulder against his.

"I get the feeling that now might be a bad time to run off and blow up our plastic currency squares on cheap entertainment like we're at some shitty human Vegas strip." Which is clearly the best way to describe going to an arcade on Panem. "I can catch up with you later. No hard feelings."

She doesn't want Dave to think that she's bailing because Rose scared her off. It would take a lot more to do that, but Rose is at least right. Neither of them want to drag Dave into this.