The Perfect Groom by Chasity Bowlin

Miss Penelope Dennings grew a conscience and made an enemy. By confessing her role in the events that nearly destroyed the marriage of Lord and Lady Mayville, she helped to bring them back together… but it has cost her everything. Her friends have turned their backs on her and she is all but a pariah in society.
Theo Blake, Lord Ralston, is a man who needs a wife. Any wife. His title and entailed estates are secure, but a significant inheritance hangs in the balance if he remains a bachelor. There’s only one problem. He’s too nice. Handsome and even rich, when compared to the rogues, rakes and general bad boys of society, there is really no comparison. All the eligible ladies simply look over him as if he were completely invisible.
But invisibility gives him a unique insight into Miss Dennings terrible situation. So Ralston makes her an offer—one she cannot refuse. But not everyone wants to see them settled in a happy union. Jealousy is an ugly and destructive force and Theo, for the first time in his life, might have to fight dirty to get what he wants. And despite the rather perfunctory nature of their courtship, he’s realized that what he wants, above all else, is Penelope…