It is a truth universally acknowledged, that when a talented author writes a popular book, everyone who can attempts to cash in on their success.
What with Pride and Prejudice entering the public domain, recent years have seen a slew of Pride and Prejudice movies and various sequels in book form. This is one of them. It was written by Linda Berdoll, who is (from her own “About the Author” blurb) a “self-described ‘Texas farm wife’ whose interest in all things Austen was piqued by the BBC/A&E mini-series of Pride and Prejudice”.
Or, in other words: Consumed by lust over a wet-shirted Colin Firth, Linda Berdoll wrote a wish-fulfillment fanfiction sequel filled with lots of hot, steamy, and explicit sex scenes. And then published it.