Bartaldi's Bride by Sara Craven

Clare usually ran a mile from powerful, sensual men like Guido Bartaldi. Only, she'd agreed to live under Guido's roof as companion to his wayward ward, the young woman clearly destined to become Guido's wife...

Horrified at Guido's marriage plans, Clare soon decided to leave-and found herself all by captive in Guido's palatial villa. Then she realized it was she who'd been chosen as Bartaldi's bride!