Tuscan Sunrise by Merry Farmer

Lady Hattie McGovern is having the time of her life, traveling with her eccentric, extended family throughout Europe on their grand tour. She has sworn to enjoy herself to the fullest on the Italian leg of their tour, and unlike her cousins, the very last thing she wants is to be tied down in marriage. She is determined to keep herself free and single.
Lord Adrian Fairfax, Earl of Whitemarsh, has been banished from home by his father, who is tired of his rakish ways and insists his son find a suitable bride. Adrian craves adventure, though, and has chosen to look for a bride abroad. But he intends to have fun before shackling himself to her.
When Hattie and Adrian are thrown together completely by accident, sparks fly. Adrian knows he’s found the bride for him, but can he convince Hattie to take the plunge? And will the dark secret that has been following the McGovern clan around Europe catch up with them at last?