All In and Falling by Simona Ahrnstedt

The two first novels in the Only One Night series by Simona Ahrnstedt.

The plot takes place in  Stockholm, New York and Chad among Sweden's upper class and world of finance.  It is  love stories / erotic novels. In "All In " Natalia De la Grip and corporate raider  David Hammer are the main characters and in "Falling "it is Nathalias younger brother - playboy Alexander De la Grip and the idealistic doctor Isobel. In this novel the eroticism is S&M.
I was not captured by the stories, so I won't be reading the last novel in the series: "Risking It All", but the books are bestsellers, have  good reviews and are translated in several different languages.