Something else which recently occurred to me is there's a lot of talk about Mao needing help sharing his thoughts and feelings, but Nanoka has probably gone her whole life not really talking to anyone.
She has friends yes, but they don't know her. It doesn't seem like she ever talked much about what happened to her, and she obviously can't tell them about Mao. She has no one at home to vent to either. If you think about Kagome she was close enough to her friends where she felt comfortable sharing certain information, and she had a whole family to confide in.
Nanoka has no one. No one who can understand what it's like to be in her position but her own self or who can offer advice. Even Mao, he doesn't know what she's dealing with in her world. So it's no wonder she gets too in her head to the point she's always doubting herself and convinces herself she shouldn't tell Mao about the Byouki and Sana.
Have really enjoyed reading everybody's takes on this!
Along similar lines I find it interesting how differently Nanoka and Kagome deal with the balance between their two worlds. I'm sure on a practical level Rumiko Takahashi got the whole modern day shenanigans out of her system with Rinne, so maybe she's not too bothered about exploring that side, but I really get the sense Nanoka has little to no connection to the modern era. Once she learned the truth about her grandpa she very quickly starts to treat Mao and the Taisho era as her home, whereas I feel like for Kagome it was more a sense of duty for a while. It's not like Nanoka's given up on her studies, but she's not going to the same effort Kagome did.
And....minor spoilers