Spells to Mend Broken Hearts by Marissa Macy

Halfway through her freshman year, Alex, sidelined by a field hockey injury, has moved with her family to the wet, windy Oregon coast, where her parents' marriage is coming apart. On her birthday she finds her grandmother's old book of small magic and performs a ritual to attract a friend, and the next day confident, tarot-loving Tess appears. The two grow close working spells from the book on their problems, but when Tess wants to use its magic to win back her ex-boyfriend, Alex has to face that her feelings for Tess may be more than friendship, and that some things magic cannot fix.