Unspeakable — Caroline Pignat

On her first voyage as a stewardess aboard the Empress of Ireland, Ellie is drawn to the solitary fire stoker who stands by the ship's rail late at night, often writing in a journal.
Jim. Ellie finds it hard to think of his name now. After their wonderful time in Quebec City, that awful night happened. The screams, the bodies, the frigid waters … she tries hard to tell herself that he survived, but it's hard to believe when so many didn't.

So when Wyatt Steele, journalist at The New York Times asks her for her story, Ellie refuses. But when he shows her Jim's journal, she jumps at the chance to be able to read it herself, to find some trace of the man she had fallen in love with, or perhaps a clue to what happened to him. There's only one catch: she will have to tell her story to Steele and he'll “pay” her by giving her the journal, one page at a time.