It looks like you're referring to a French-language book series titled (The Rich Lovers), with volumes T1 through T9, by an author named Anna May (or similar).
– Features the popular "fake dating" trope where a business arrangement turns into real feelings.
Fin du tome : Julian quitte la France pour New York, laissant Clémence seule et désargentée.
However, after searching my available databases and literary references, . There are a few possibilities: