Dog-Eared Book Pages

A little while ago I leant a friend a book (the first of a long series). Now, I’m very careful about who I lend my books to. I’ve been caught out in the past when I’ve handed out books under the understanding they were being borrowed, but to never see them again. I learnt. I only part with my reading material if I am sure it will be returned. The friend I trusted with my book did return it, she didn’t let me down there, BUT my beautiful book came back to me dog-eared. Yes, she’d marked her place by turning the corners of the page down.

What to do? Naturally she wanted to borrow the rest of the books in the series (there are 6), but I wouldn’t put the rest of my books through that level of pain. I leant her the books with a pile of bookmarks. I hoped that was enough of a hint!
I’d love any suggestions you might have on how to lend books with instructions not to dog-ear the pages!