Moonlight Encounter by Nina Jarrett

Lord Aidan Abbott investigates Mr. Smythe but compromises his daughter, Gwen, at a ball in front of a crowd of important guests.
In this steamy historical romance, the heir to a viscountcy is determined to protect his sister, accidentally ruining a young woman while searching her father’s home. Now he will need to choose between his crusade and the growing love between them.

He feels guilty for failing his family …
Lord Aidan Abbott neglected his duties as a chaperone when his parents left his little sister in his charge. Because of him, Lily was forced to wed under a cloud of scandal. Now Aidan must solve a murder to keep his sister and her new husband out of danger.

She is caught unawares …
A mysterious lord interrupts Miss Gwendolyn Smythe while she is taking air on the terrace. Unfortunately, they are discovered together, forcing her to marry a man she has never met before to quell the scandal. Now Gwen is determined to make the best of their new marriage, with or without his cooperation.