The Loneliest Girl in the Universe by Lauren James

Can you fall in love with someone you’ve never met, never even spoken to – someone who is light years away?

Romy Silvers is the only surviving crew-member of a spaceship travelling to a new planet, on a mission to establish a second home for humanity amongst the stars. Alone in space, she is the loneliest girl in the universe until she hears about a new ship which has launched from Earth – with a single passenger on board. A boy called J.

Their only communication with each other is via email – and due to the distance between them, their messages take months to transmit across space. And yet Romy finds herself falling in love.

But what does Romy really know about J? And what do the mysterious messages which have started arriving from Earth really mean?

Sometimes, there’s something worse than being alone . . .
 
- Goodreads Summary