Never leave a book you plan to borrow OUT on the shelf in the household it belongs.
Chol hamoed is a good time for catching up with yourself, with friends, and with G-d. And your reading (esp. Jew reading.) So I was over at my friend’s house, looking through her family’s book shelf, and I see a book that I have wanted to read for a few years, basically since it was first published. (That one on Mystical Music or something, by Rabbi Trugman.) So I asked my friend if I could borrow it, and she said “sure” and I put it on the edge of the bookshelf to take before I leave. (And wrote a run-on sentence.)
Along comes her mom, sees the book, and starts reading. Now if her mom starts reading it, you know I can’t borrow it until she’s done. That would be rude. So it could be a good few months. And when your friend is engaged and getting married in a few weeks, you might not be in their house for a LOOOOOOOOONG time.
Man plans and G-d laughs, again!