"I ALREADY MENTIONED THAT I HADN'T DECIDED UNTIL YESTERDAY!" How many times did he want her to explain the same thing? Staring at him a moment as Ron told her that he wanted to celebrate their engagement, Hermione wondered how she was supposed to know that when he didn't say anything. She was distracted from asking however, as he kept speaking.
"Oh for goodness sake!" she responded. "My parents like you just fine. You want to know why they didn't invite you? It's not just a trip away because of what happened at Flourish & Blotts, they also wanted to do one last thing as a family. Because now we're engaged? We've created one of our own. That's the only reason they didn't suggest it and the only reason I didn't ask you."
Throwing her hands up in exasperation as Ron went for his coat, Hermione glared in his direction. "That's just wonderful. You get your knickers in a twist over my leaving for a few days, but it's fine for you to just walk out on me? No one was trying to exclude you, Ron, but go ahead. Celebrate by yourself. I hope you have a good time."