The Duke's Unexpected Courtship by Georgia Griffan

Compared to her sister, Adeline is plain. She has no hope of making a brilliant match. Instead, she must be practical. A gentleman with a moderate fortune will do well enough for her. There will be no grand titles or London Seasons or rich dresses with fine adornments. But Adeline has made her peace with that. As the second daughter of a mere baronet and a plain-faced one at that, expecting a wealthy Lord to sweep her off her feet is a fool's game. No, of the two of them, her older sister will be the one to make a brilliant match, Adeline must settle for any man of means who will have her.

The Duke of Aberlay is the catch of the Season. Wealthy beyond all measure, his family sits at the very head of the ton. The highest ladies in the land throw themselves at him, hoping to earn that coveted title, The Duchess of Aberlay. But so far, none have managed to capture the Duke’s attention.

Adeline knows she is far below The Duke of Aberlay’s notice. The Duke will marry the wealthy, well-connected, beautiful daughter of a peer, all things Adeline is not. So why does the Duke keep seeking her out? And why does Adeline’s treacherous heart beat faster in his presence? After all, it would be a very impractical thing indeed for the plain-faced daughter of a baronet to fall in love with a Duke.