The lack of communication is a little frustrating but I think it makes sense for Naori to close herself off when she's uncertain like this. She'd always been a loner prior to the start of the story and she's not used to opening up to people about these things. I think this arc won't just be important for Hinata's goals going forward but also for Naori to understand what it really means to be with Hinata, not just as a bartender but as a partner.
I think much more than Naori being a loner previously, it's that she knows she can't talk about this with Hinata. Hinata wants to become human, but Naori is reconsidering whether that even makes sense, or is the best solution, or even any kind of solution at all. So Naori needs to think about it, and really figure out the answer in her own head, before she can talk to Hinata and potentially change Hinata's mind. If Naori were to talk to Hinata about what she's thinking about, I think Hinata would shut it down and say that she's going to become human.
I think it's also guilt on Naori's part... she's starting to think that Hinata being an ogre is a key part of her, and that Hinata is working to give up a fundamental part of herself in order to be with Naori. Which is incorrect of course - Hinata wanted to become human even before she met Naori - but wanting to become human to be with Naori might be the strongest reason now.