The Duke’s Bride in Disguise by Claudia Stone

When poor orphan Ava Smith comes face to face with a girl who looks exactly like her, she is certain she has seen a ghost! But, Lady Emily Fairfax, is no ghost and is sure that she and Ava must be long lost twins. Despite her better judgement, Ava allows Emily to convince her to swap lives for a month, in order for Ava to scupper Emily’s engagement to a cold-hearted, brute of a man.
Imagine Ava’s surprise when Emily’s betrothed turns out to be none other than her unrequited crush, the Duke of Kilbride!

Raff Alexander Hamilton, the Sixth Duke of Kilbride, knows that he must do his duty to the line by marrying and procuring an heir. Love was never in the equation in his search for a bride. All that he required was a lady who was well-bred, quiet and biddable—and he thought that he had found just what he was looking for in Lady Emily Fairfax.
Imagine his surprise, when overnight, his betrothed goes from meek and compliant to outspoken, alluring, and decidedly unimpressed with him.

As Raff battles to woo his bride to be, Ava must navigate the sumptuous world of Regency London, while trying desperately not to fall in love – no matter how much her heart wants it.