Books like Quade by Bronwyn Jameson

Convenient Bride for the King is a romance novel by Kelly Hunter that explores themes of love, duty, and destiny within a fictional setting.

HE WAS A ROGUE AND A HERO AND HE HAD MARRIED HER FOR HER MONEY Everyone in bon ton knew that Lord Hubert Challenge had married country mouse Mary Tyre for her dowry, but no one had yet guessed that Mary had actually fallen in love with her husband! But none of them, of course, understood the incredible passion that was bringing their marriage to the brink of destruction--the passion for vengeance. First, Hubert continued to see his beautiful mistress, Clarissa. And Mary would try anything to get her handsome husband's attention - sumptuous clothes, a saucy manner, even flirting someone else's husband to make Hubert jealous. Until she learned that two could play at that particular game... And so they criss-crossed each other, these two lovers--until fate stepped in and turned them around... in a most extraordinary way.

After a one‑night affair, secretive operative Quade Westmoreland discovers he has three sons with Cheyenne Steele and vows to claim both her and their children, even as she resists his advances.