I would like to recommend a book about boundaries to a friend, starting from very basics. I don't necessarily want her to come here... but I want to help her and she's struggling with that issue in her marriage.
Accept that there is only one thing you can change in life and that is you
It seems to me like both books rely on Christian background and neither her nor her husband are very religious. Is that approach very strong in these books?
Accept that there is only one thing you can change in life and that is you