I spent most of my time with that book trying to untangle the central scheme, honestly. So the core setup is this business tycoon who's under immense family pressure to be married for image reasons, but his real girlfriend is a famous actress whose career would tank if the relationship went public. He ends up hiring a down-on-her-luck woman who needs the money—usually someone with a specific skill, like being a chef or an event planner—to act as a fake fiancée and later wife for the public eye.
The main plot drivers are the contractual rules slowly breaking down as real feelings develop, all while they have to maintain the charade at galas and family events. There's always a third-act conflict where the real girlfriend causes trouble or the family uncovers the contract, forcing the two leads to confront whether their arranged relationship has become the real thing. It's a classic blueprint, but the tension comes from the small, stolen moments where the pretense drops.
I remember the version I read had a subplot about the stand-in starting her own business using the salary from the deal, which I actually found more engaging than the main romance sometimes.