I first studiedElisabeth Kubler-Ross' "five stages of grief" in high school. Since then, I have accepted her theory. As Michael Shermer suggests in this articlein Scientific American there is little evidentiary support for her thesis.
Part of the problem, I believe, is that people like to make life more tidy than it actually is. For example, Freud suggested that people move through five stages of pyschosexual development; Lawrence Kohlberg postulates our moral development has six stages; and, of course, Kubler-Ross was of the opinion that we experience five stages of grief. (Ironically, I once read that near the end of her own life Ross was bitter at the thought of her impending death — apparently, she never reached the "acceptance stage.")
If we accept these theories as given, it makes unlearning that much more difficult. To really unlearn it helps to view life as far complex than many of our leading social scientists would like us to believe.