The movie rights have been purchased for M. L. Stedman's THE LIGHT BETWEEN OCEANS.  wonderful book about a lighthouse keeper and his wife. Tom is a WW I veteran, one of the 'lucky ones', he has lost a limb nor his mind but he deliberately seeks the solitude of an island off Australia.  He meets and marries, Isabel. But times on the island are tough for Isabel as she suffers multiple miscarriages and a stillbirth in just four years time. When a boat with a dead man and a young baby washes ashore, Isabel convinces Tom to let her keep the baby as their own, but the consequences to her actions may be dire.  Similar books are:

The sandcastle girls: a novel by Chris Bohjalian

The orchardist: a novel by Amanda Coplin

The secret keeper: a novel by Kate Morton