Seduce Me At Sunrise by Lisa Kleypas

This book has a LOT going on. Even though it's the second in the series it goes back in time for several chapters of set up, there's a weird murder doctor love triangle that serves no purpose, and the pairings from book 1 and book 4 in the series get a lot of time on page. There is also a sex cabin that is a significant portion of the book and absolves all sins and you should totally read this.