One of the ways I have tended to look at NA is as the story of Catherine thrown into a new situation (or new situations) and not wanting to make a wrong (improper, undignified, rude, socially unacceptable) move. Secure at home, she arrives at Bath, where the "rules" are often different. She trieds to fall back on her upbringing (the Fullerton "rules") wherever possible, but sometimes she cannot.

Her first night at a ball, she feels lost and unsure; but at her next she meets and somehow feels at home with Henry (a good sign if Henry becomes interested on a long-term basis).

Isabella seems to know the Bath "rules" and has been properly introduced through Mrs. Allen, so Catherine trusts her.

She meets John Thorpe and is on shaky ground again. Her Fullerton experience tell her John is not to be trusted, but he has the sanction of both James and Isabella; so Catherine is caught in a limbo between her experience and loyalty to family and friends.

So having placed Catherine in Bath and anxious not to make a misstep, JA has set Catherine up with a succession of new experiences that catch her betwixt and between--what, I suspect, we would now call shades of gray, but in a world (in Catherine's time) that frequently only admitted to recognizing black and white.