I know this is a sweet slice of life manga but that part between Teto and Chise really make me worry about something would happened to Teto and Chise feel lonely whenever she thinks about Teto
Yeah, It was a tone shift for sure. It's eluded too a little earlier in the novels, with how they are laid out. But It's a pretty core part of the series.
I'll spoiler tag this, just cos' It's a difference from the Novel to the Manga, but It's honestly not REALLY a spoiler:
This is also part of the reason the left Daryl earlier, because she had a feeling with a huge mana pool people would start treating her differently after a few years when the realised she would age a lot slower. She wants a place she can belong.