Never Marry a Scandalous Duke by Renee Ann Miller

A thoroughly roguish nobleman and a devoted lady entomologist have absolutely nothing in common—or do they? Love is far from scientific when it truly blooms . . .

In the eyes of the ton, Lady Sara Elsmere is so firmly on the shelf, she might as well be nailed in place. Not that Sara minds. She is far more concerned about her study of butterflies than society’s gossip. Of course, it’s also true that the nervous laughter that ruined Sara’s debut—and every social event thereafter—is a bit embarrassing. She can hardly help it—men are quite nerve-wracking. Except for one: the rake who pulls her into a dark room during a costume ball and kisses her senseless. He doesn’t make her titter, he makes her burn . . .
Ian McAllister, the Duke of Dorchester, is perfectly satisfied to remain a rogue for the rest of his days. But when he finds he has kissed the wrong shepherdess, albeit a decidedly luscious one, he’s faced with a dilemma. His indiscretion with an innocent may cost him a lucrative business arrangement—and his two scapegrace wards need a maternal influence they can’t scare away. Promising Sara the use of her dowry to fund her studies seals the pair’s businesslike deal. But as they embark on their life together, they discover that their mutual attraction has sparked a desire not easily tamed—and certain feelings each of them are surprised to own.
Can their matrimonial experiment possibly end in real love?