"Standalones that you wish had a sequel or the last book in the series that you wish wasn't the last."
1. P.S. I Still Love You by Jenny Han (and the sequel is in fact coming for this book!)
2. My Life with the Walter Boys by Ali Novak
Again I didn't find 5 books. I don't read a lot of standalones and am usually happy with the endings of series and don't feel like I need more books.