A Mistress by Rumor. Diamonds of London, #11

Opposites attract and desire clouds judgment, but perhaps that's what an unlikely couple needs. Widowed two months after she married, Constance Knight thought to put herself back onto the Marriage Mart once her mourning period ended. However, the evening she wished to stretch her legs and take in the fresh evening air, she's nearly robbed. When a handsome stranger rescues her from such a fate, rumors begin to swirl, and they are quite erroneous if intriguing. Mr.
Gregory Hamilton is a barrister, but he also dabbles in boxing when he's not in the office; the fighting is the same. While returning home one evening, he leaps from his carriage when he witnesses a woman being assaulted on the pavement. After putting down the threat with a couple of well-timed punches, he bundles the attractive woman into his arms to settle her nerves. By the time he escorts her into the house where a rout is being thrown, gossip puts them together in the most scandalous of ways. As the whispers and stares intensify over the following days, Constance wishes to fight back and defend her reputation, but a chance conversation with Mr.
Hamilton has her changing her mind. When the young widow is receptive to his scandalous idea, Gregory is most pleased to take her on as his mistress in truth. Except once they share intimacy, everything changes. Yet they're from different worlds and there can be no future between them. Only if they're honest with themselves will they perhaps have an unlikely romance. Unless fate intervenes.