I loaned a book to a friend once and after many months it was not returned so I asked quite politely if she has finished with it could she please give it back when we next meet. Her reply was I had finished it and loaned it on the another friend - unknown to me. I was quite upset about it as the book was not hers to loan. If she had asked me that would have been a different matter. For the sake of peace etc I did not take it any further with her. But ........
A lesson from that day to this - never be a borrower nor lender.