No idea why it was called the Duchess War... she didn't want to be duchess? Her duchess mother in law didn't want her to be duchess (although she appeared in about 10% of the book)? 
 The beginning was really interesting, then the premise became dull because it wasn't clear why she didn't want to be a duchess... until the BIG SECRET was finally out. 
 The heroine was a bit annoying at times, but overall likable. The hero though was just too-good-to-be-true... he had no negative traits in his character except his insecurities. And of course, his less than credible sexual inexperience. He reminded me of a teenager, which, come to think of it, emotionally he was. So was the heroine.