The Flatshare by Beth O'Leary

 Tiffy has just broken up with her boyfriend, Justin, who has found someone new and wants Tiffy out of his apartment. She is an underpaid editor so desperately needs to find an affordable place to live. Leon is a hospice nurse who needs money to pay his brother's legal bills. He works nights, she works days, so they agree to share his flat during the week and he will stay with his girlfriend, Kay, on weekends. They start leaving each other Post-it notes and soon start becoming friends--even though they've never met in real life. Tiffy is feeling good about her new life--then Justin starts popping up at her work events, which she finds very unsettling.

While it is mostly a romantic comedy type of story, it does have a serious underlying plot--dealing with a manipulative ex (Justin). I loved Tiffy and Leon, his unfairly convicted brother, and her best friends Mo and Gerty. I started reading this book yesterday afternoon and stayed up way too late last night to finish it.