I am not sure I have the pleasure of understanding you in the context of fan-fiction.
Certainly you are correct if you are wishing to replicate Austen's style, message, and personality. But then, if one were to do that, then the result would look (or should look) dramatically identical to the original.
In the case of fan fiction, unless the author intends to imitate the author, there is plenty of leeway for the non-canon. Not only in pairings, but also in most other aspects.
Some of the Toddles series on this site would probably not have received Miss Austen's whole hearted approval.
Certainly you are correct if you are wishing to replicate Austen's style, message, and personality. But then, if one were to do that, then the result would look (or should look) dramatically identical to the original.
In the case of fan fiction, unless the author intends to imitate the author, there is plenty of leeway for the non-canon. Not only in pairings, but also in most other aspects.
Some of the Toddles series on this site would probably not have received Miss Austen's whole hearted approval.