Regency Romance read 2010. Its the h's bday and the H goes to see her. They're backstage (h is in a play i think). The h is somehow compromised by the H and as that happens a bunch of people are suddenly there, especially lord and lady gossip a lot.

[Sassy]

The h's grandma then decides that they will tell everyone that the H and h are engaged.One thing that stood was that the h had met the H at a ball but decided that the H was too much and so she decided that she prefers the H's cousin.

[Spockles]

To Desire a Wicked Duke by Nicole Jordan?

[Brenna]

This does sound like To Desire a Wicked Duke as suggested above.

But if it’s a different book, I’m interested...so bumping

[JennyJ]

Bump

[Kris]

Note: Sassy (OP) was last active on the site in February 2020.

Here's a Google Books preview of To Desire a Wicked Duke by Nicole Jordan - Spockles and Brenna's suggestion.

https://books.google.com/books?id=mvm... There are different cover images.