The Transit of Venus by Shirley Hazzard

The tragedy is not that love doesn't last. The tragedy is the love that lasts. Two sisters, Caroline and Grace Bell, leave Australia to begin a new life in post-war England.

Courted long and hopelessly by young scientist, Ted Tice, strong-willed Caro is to find that love brings both betrayal and hope. The milder Grace seeks fulfilment in an apparently happy marriage. But as the decades pass and their paths weave and cross across the world - from Sydney to London, New York to Stockholm - two slow-burning secrets wait in ambush for them.