The Duke and I - Julia Quinn

After enduring two seasons in London, Daphne Bridgerton is no longer naive enough to believe she will be able to be marry for love. But is it really too much to hope for a husband for whom she at least has some affection?

Her brother's old school friend Simon Basset - the new Duke of Hastings - has no intention of ever marrying. However, newly returned to England, he finds himself the target of the many marriage-minded society mothers who remain convinced that reformed rakes make the best husbands.

To deflect their attention, the handsome hell-raiser proposes to Daphne that they pretend an attachment. In return, his interest in Daphne will ensure she becomes the belle of London society with suitors beating a path to her door. There's just one problem, Daphne is in very real danger of falling for a man who has no intention of making their charade a reality...