She was amazing in a sort of unsubtle way; crudely amazing--I thought.

Why crudely?
I don't know.

Perhaps because I saw her then in a crude light.

I mean this materially--in the light of an unshaded lamp.
Our mental conclusions depend so much on momentary physical sensations--don't they?
If the lamp had been shaded I should perhaps have gone home after expressing politely my concern at the Fynes' unpleasant predicament.
Losing a girl-friend in that manner is unpleasant.

It is also mysterious.