Highland Champion by Cynthia Breeding

Lorelei Caldwell is elated about her first season in London. For the next few months, she and her best friend can indulge in balls, flirting, and enjoying the delights of London society without any family interference. This season is for adventure, not marriage. But her adventures are short-lived after the arrival of her friend’s brawny, dark-haired Highlander brother, Alasdair MacGregor, who insists on standing as chaperone.
Officially, Alasdair is in London to reclaim lands that rightfully belong to his clan. Unofficially, he’s here to figure out how best to win Lorelei’s hand in marriage. But London proves to be full of complications… especially when she begins matchmaking him with someone else.
Except Lorelai’s plans have backfired and she is finding herself craving Alasdair’s attentions. Her longing for freedom could come at a high price, unless Alasdair can salvage her reputation… without destroying her independent heart.