Came a Stranger — Mair Unsworth

When Charlotte Laurie embarked on a voyage to America, a tragic twist of fate brought her to a small Welsh island instead. There she was placed in the tender care of Mark Waldron, a handsome young doctor. Soon Charlotte realized she was falling in love with Mark, even though another woman had won his favor.
But just as she thought she had captured Mark's heart, Charlotte's involvement in the lives of the townspeople turned him against her. Now she had nowhere to go, no-one to protect her.
Then a visitor came from England -- a man who had proposed to Charlotte a few months before. He begged her to reconsider. Here was the opportunity she had waited for -- the only realistic solution to her problems. Why, then, did Charlotte desperately hope to be rescued from the very escape he offered?