Faithful Series by Janet Fox

Sixteen-year-old Maggie Bennet's life is in tatters. Her mother has disappeared, and is presumed dead. The next thing she knows, her father has dragged Maggie away from their elegant Newport home, off on some mad excursion to Yellowstone in Montana. Torn from the only life she's ever known, away from her friends, from society, and verging on no prospects, Maggie is furious and devastated by her father's betrayal. But when she arrives, she finds herself drawn to the frustratingly stubborn, handsome Tom Rowland, the son of a park geologist, and to the wild romantic beauty of Yellowstone itself. And as Tom and the promise of freedom capture Maggie's heart, Maggie is forced to choose between who she is and who she wants to be.

Kula Baker never expected to find herself on the streets of San Francisco, alone but for a letter of introduction. Though she has come to the city to save her father from a cruel fate, Kula soon finds herself swept up in a world of art and elegance - a world she hardly dared dream of back in Montana, where she was no more than the daughter of an outlaw. And then there is the handsome David Wong, whose smiling eyes and soft-spoken manner have an uncanny way of breaking through Kula's carefully crafted reserve. Yet when disaster strikes and the wreckage threatens all she holds dear, Kula realizes that only by unlocking her heart can she begin to carve a new future for herself.