The Parlor Game by Ashtyn Newbold

Love might be the most dangerous game of all.
After enduring a loveless marriage, Anne, the widowed Lady Daventry, hopes to find happiness with her first love, Miles, upon his return from India. Knowing his plans to settle in London, she accepts an invitation to a house party in Town, hosted by the eccentric Lady Tottenham. When the first night of the party consists of a scandalous secret parlor game, she finds an unwelcome guest amongst the group: Miles’s scoundrel of a younger brother, Alexander.
Alexander Holland came to London with one objective: take back the money his brother stole from him. Becoming embroiled in a lavish party full of riddles and matchmaking schemes hadn’t been part of the plan. Appalled by Anne’s loyalty to Miles, Alexander suggests a wager over a game of chess. To be sure she truly loves Miles, she must court a man of Alexander’s choosing prior to Miles’s return.