From London, With Love. London Steampunk: The Blue Blood Conspiracy, #6

With London finally at peace, there is only one threat remaining to the stability of the monarchy.. The queen is without an heir. Queen Alexandra is done with marriage, but as always, the Duke of Malloryn has a plan. With Malloryn insisting upon an heir for the realm, Alexandra reluctantly agrees to accept a husband. But who? With Europe's most eligible bachelors in London to attend her exhibition, she finds herself pining for the only man who has never betrayed her.
The only man she wants. And the one man she cannot have. A queen's duty is never done. Alexandra's feelings for her dearest friend Sir Gideon have always been warm, but a stolen kiss pushed a friendship into dangerous waters. How can she explain that she has never known desire before? How can she stand to be in the same room as Gideon, without betraying her feelings? And how can she marry someone else? But there's an assassin on the loose, and while she may currently be at odds with Sir Gideon, he's the only man who can save both her wounded heart-and the future of the realm.
Foreign princes and meddling dukes, bedamned.