I read cozy and historical mysteries, a bit of Paranormal/UF, and to mix it up, I read science and gardening books on occasion.
Still relevant, still timeless. I think. Re-reading this as an adult nothing jumped out at me as anachronistic.
My parents never went through a divorce, so I can't speak to the accuracy of Karen's POV, but I do know that as a kid it gave me insight into what my friends might be going through; hopefully it stopped me from sticking my foot in my mouth (as much).
Odd what you remember: Karen meets a new friend, Val, who reads the New York Times every Sunday cover to cover. That was the most memorable part of the book for me - that and Val's foot shaped rug.