The High Season by Judy Blundell

The Orient isn't the Hamptons and that is how the residents would like to keep it until Adeline rents out Ruthie's house for the summer.
She has to rent out the house because that is the only way that she and her soon-to-be ex can keep it. The added income from a few weeks in summer and they can just about squeak by for another year and the whole summer feels like a goldmine. Adeline brings money and fame along with her stepson and this kicks up a fever to grab those patrons of the arts dollars for Ruthie's museum. Things go from bad to worse in every aspect of her life, work, and friends. Summer in this quaint little neck of the beach will never be the same. Ruthie keeps treading water hoping someone will throw her a life preserver before the hurricane hits. Classic beach read with all the best backstabbing, gossip, and a juicy love interest - all the best of how the have and have-nots spend the summer in New York.