Change of Heart — Rachel J. Good

Lydia Esh's younger sister Emma is running wild during rumschpringe, causing the family major heartaches. Although it means risking her reputation, her job as a schoolteacher, and her courtship with Jakob Zook, Lydia attends parties to watch over Emma and protect her sister's virtue.
 
When Emma begins a relationship with Kyle, an Englischer, Lydia teams up with Kyle's older brother, Caleb, to keep the couple apart. As Lydia and Caleb spend time together keeping an eye on their siblings, Lydia falls for this forbidden love. But she fights her attraction and determines to stay true to her faith.
 
Caleb confesses his feelings to Lydia. She admits her attraction to him, but she's made her decision to join the church and marry Jakob Zook as her family is pressing her to do.
 
Will Lydia stay true to her faith even when it means giving up the things that are most precious to her?