Sunburn by Chloe Michelle Howarth

It's the early 1990s, and in the Irish village of Crossmore, Lucy feels out of place. Despite her fierce friendships, she's always felt this way, and the conventional path of marriage and motherhood doesn't appeal to her at all. Not even with handsome and doting Martin, her closest childhood friend. During a long hot summer, a spark with her school friend Susannah escalates to an all-consuming infatuation, and, very quickly, to a desperate and devastating love. With the end of school and the opportunity to leave Crossmore looming, Lucy must choose between two places, two people and two futures, each as terrifying as the other.