The girl was as wild as a hawk, and although she was marked by a fine fastidiousness, would revolt from a narrow-minded prig.

Lister was not a prig; his blood was red.
In another sense, perhaps, the thing was ridiculous.

Barbara was rich and ought to make a good marriage, but good marriages sometimes brought unhappiness.
Human nature was stubborn; one paid for forcing it to obey the rules of worldly prudence.

Then Barbara had a romantic vein.

She would risk all for her lover and not grumble if she were forced to pay for her staunchness.