The Gum Thief. Douglas Coupland

Roger is a middle-aged and divorced 'aisles associate' at a Staples outlet. His co-worker Bethany is facing fifty more years of shelving Post-it notes. Then Bethany discovers Roger's notebook and finds that he's writing diary entries pretending to be her - and weirdly, he's getting it right. Bethany and Roger strike up a secret correspondence, and as it unfolds so too do the characters of Roger's work-in-progress, Glove Pond, a Cheever-era novella gone horribly, horribly wrong.