The older one really abused her trust, that end of chp2 when the younger one tries to leave and she says come inside.. I'm not too comfortable with this.
Good. It would be more concerning if you were.
I like to give the benefit of the doubt to the author but this seems really well done.
What the older lady did was wrong? Absolutely. That's probably the point. What she did wasn't malicious in her eyes and she meant no harm but it is a crime and for good reason.
This manga seems to have looked at all the innocent, adorable age-gap and decided to show us what it could (or perhaps more likely would) be like.
Also, that nonsense of pushover adult and far too smart/manipulative student is completely thrown out. This is more like what the gap would cause. A pushy (to be nice) adult and a naive child who is left bewildered afterwards. Filled to overflowing with thoughts she's never had and emotions she's never felt.
This is good. I'm thoroughly enjoying it and the implications of what they have done. How the two handle it from here. Though i do think these two may never become a couple, ever. And that we are seeing a very impactful, and influential, time of our protagonist's life.