That's a good question. Perhaps Anne's fidelity to the memory of her first romance would be seen with more value in her day.

Perhaps today, we would just pity her for not being able to forget it.

Perhaps Austen too mocks her society's emphasis on fidelity - just a little. Before your post, I never thought that society would or could admire a young woman for holding on to such feelings (though it may not hate her for it). Perhaps the line below is funnier than I ever expected.. (and I found it funny anyway.)

No second attachment, the only thoroughly natural, happy, and sufficient cure, at her time of life, had been possible to the nice tone of her mind, the fastidiousness of her taste, in the small limits of the society around them.