The Summer I Turned Pretty Trilogy by Jenny Han

 Belly has always lived for the summertime because it means all her favorite things: swimming, the beach and the Fisher boys, Conrad and Jeremiah. She has spent every summer with them at Cousins Beach for as long as she can remember. She has always been in love with Conrad and finally, one summer, it seems like he might have feelings for her too. But it turns out, so does Jeremiah.

As the summers go on, Belly has to choose between two brothers who love her as she comes to the realization that she will have to break one of their hearts.

The summer I turned pretty part one

It’s not summer without you part two 

We’ll always have summer part three