Well, I will share what I know unless someone who is more experienced on the comes forth. Actually the wikipedia page provides valuable insight to the matter. The model was based on people who were experiencing death themselves, not grieving for a loss. Additionally, you don't go through these emotions step by step. Instead, they act like different sets of emotions that can occur throughout the grieving period. That means you can be in denial and anger at the same time, and be in acceptance and anger the next day. The thing is, since the theory wasn't based on people who were grieving, it would be wrong to apply the theory to them. I don't think there is a model for this, it may lead to psychopathology of course and then it would be within the realm of clinical psychology at that point. Anxiety, depression, or emotion regulation problems for instance.