The Flight of the Swan — Eleanor Farnes

Considering her narrow, rigid upbringing, it was not surprising that Philippa had been a complete "ugly duckling", but now, in her new-found independence, she was rapidly turning into a swan. She found a pleasant job, with an agreeable family, and a most attractive man was taking an interest in her.

And then, just as her happiness was at its height, the jealousy of another woman threatened to destroy it.