I bought the 1st edition (currently, 3ed) of this book over 20 years ago, hoping to get by some of the difficult relationship with so-called friends & colleagues. And some relatives as well.
I think I still got nowhere & certainly none the wiser after more than halfway thru the book. Yes, right, so up till now, I didn't haven't finished reading it, because relationships are just too complicated.....
Then I realised I could have gotten free advice, concisely in 2 sentences, from Peter the apostle.
Be careful to live properly among your unbelieving neighbors. Then even if they accuse you of doing wrong, they will see your honorable behavior, and they will give honor to God when he judges the world. (1 Pet 2:12)