How I Live Now by Meg Rosoff

Daisy is fifteen and has stopped eating as a form of protest against her father turning from her to his new wife and unborn child, so despite rising international tensions he sends her to Brtian to stay with her cousins just as they become seperated from their mother as the UK is invaded and occupied while their troops are elsewhere fighting other people's wars. Trapped in the cousins' farmhouse Daisy's new family are the sweet loving Piper who has always wanted a sister, the older bossy brother Osbert and the 15 year old twins Isaac and Edmond who differ only in the colour of their eyes, that Edmond smokes and he seems to know exactly what Daisy is thinking. A sad lovely story of occupied life, young love and desperation