Dangerous Illusions by Amanda Scott (Dangerous #1)

Engaged by proxy to a man she’s never met, Lady Daintry Tarrant is dismayed when the war hero returns, introducing himself as her fiancé, Lord Penthorpe. She cherishes her independence and has turned away many suitors, but this one she must marry. Penthorpe is completely captivated by Lady Daintry—but he’s not who he claims to be.

Penthorpe and Lord Gideon Deverill fought together at the battle of Waterloo, and when Penthorpe fell, Gideon assumed his identity in order to see the beautiful Lady Daintry. Gideon knows there’s bad blood between Lady Daintry’s family and his own, but he’s smitten with Daintry and determined to reunite the bitterly feuding clans. When a ghost from Gideon’s past appears, he could lose everything—including Daintry’s love.