Yeah, I got this bug also in Patch 7..., but Arabella is not present when I first visit the grove, neither her parents. If I talk to Kagha for the first time she says "Go on. Say it. You think I'm a monster." I only got one long rest.
odd. I've done some playing around with different characters of late and have gotten that dialogue correctly many times in Patch 8. Did you try another new character to see if it was a one off?