SOLVED. Historical romance where lady asks neighbor duke to teach her about passion [s]

[Beebs]

Lena wrote: "can't remember the author or title. I know that in the beginning the lady watches the duke in his garden with another woman and then decides that he is the perfect person to teach her about passion..."

Possibly Sarah Maclean's , certainly has a garden scene like you describe.

[Aerulan]

Long shot but Everything Forbidden by Jess Michaels has a few similar points. This one's pretty explicit, if the book you remember isn't then it's definitely not the one you're looking for but it begins with the h seeing the H out in his gardens/grounds of his estate with another woman.

[caracal-eyes]

Probably not it, but a similar plot to what you mentioned: The Lady's Tutor.