You and Me on Vacation by Emily Henry

Poppy and Alex. Alex and Poppy. They have nothing in common. She's a wild child; he wears khakis. She has insatiable wanderlust; he prefers to stay home with a book. And somehow, ever since a fateful car share home from college many years ago, they are the very best of friends. For most of the year they live far apart--she's in New York City, and he's in their small hometown--but every summer, for a decade, they have taken one glorious week of vacation together. Until two years ago, when they ruined everything. They haven't spoken since. Poppy has everything she should want, but she's stuck in a rut. When someone asks when she was last truly happy, she knows, without a doubt, it was on that ill-fated, final trip with Alex. And so, she decides to convince her best friend to take one more vacation together--lay everything on the table, make it all right. Miraculously, he agrees.