I came across this book over 20 years ago when my 3 sons were in their early teens and pre-teens. The boys mother and I were divorced, and she wanted no part of this normal human practice, so I sought out resources that would help support the talks I had with each of them.
The boys each had their own bedrooms at my house and I placed a copy of this book in my oldest son's room when he was about 15 (when I discovered the book) and then in my younger son's rooms when they were about 12-13 years old when they came to visit me in the summers for 8 weeks.
I didn't think much of it for years, but recently my oldest, who is now 37, and has a 12 year old of his own, asked me if I remembered this book. I was pleased to hear how much it meant to him as a teen and how he was trying to see if he could find it still.
While its long since out of print, I consider it still to be an excellent book for teens