Can't remember name of book. Help!

[Sammygurl21]

I'm trying to remember the name of a romance novel that I read a while ago. I'm pretty sure that near the beginning of the book the heroine is up in a tree and she sees the male lead have sex with a woman at the base of the tree. After the woman leaves he talks to her letting her know he knew she was there the whole time.

Later in the book the male leads sister asks him to ruin her because she thinks that the heroine has gained the affections of a guy she wants for herself. He agrees and gives the heroine a string of pearls in a very erotic way while riding in a carriage. She later wears the pearls out not knowing that the ton know what those pearls mean. Bcause he's given other women pearls in the same manner in the past. The heroine finds out and is naturally furious.

I don't remember anything more, but if anyone might have an idea of what the name of this book is it would be great -- it was set in England in maybe regency or Victorian. Not really sure on the timeline.