Love Me Forever by Johanna Lindsey

Still mourning her mother’s death, Kimberly Richards is incensed by the determination of her father, the Earl of Amburough, to marry her off as quickly as possible—just to please the jealous lover he plans to wed. And since Kimberly harbors a deep-seated dislike of gold-diggers and the whole distasteful state of affairs, the feisty young heiress already despises the worthy suitor she encounters at Sherring Cross Estate: Lachlan MacGregor, the dashing, newly impoverished Laird of Clan MacGregor.

A tryst with the handsome, haughty Lachlan seems dubious, especially since the rogue has designs on the married Duchess of Wrothston. But strange turns and outrageous circumstances promise to lead a woefully mismatched pair to a wildly unexpected destination—where a hard, resisting heart can open to the true glories of love.