I only ever loaned one book in my life. Fatal Secrets by Richie Tankersley Cusick in 1994. The borrow-ee kept the trade paperback in her book bag for a month where it was ripped to shreds by her binders.
Never again. You ruined it for everyone, Marion
Here’s my “loaned out and never got back and I regret it”:
The Kite Runner by Khaled Hosseini
I admire Bridget Riley’s positivity. I am somewhat less graceful about that purloining.