There are many factors which affect how a person experiences his or her grief. Your history of loss is a major factor—if you have had many prior losses in your life, it may be harder and take more time to mourn this current loss. Did you mourn your previous losses? If not, these prior ungrieved losses may make the current loss feel unbearable. Each new grief rips the scab off prior losses.
Your state of being when the loss occurred also affects you. Were you sick, exhausted, burned out or depressed before the loss? If so, this may make the loss much more complicated to grieve. Grief takes energy! Were you involved in drug or alcohol abuse at the time of the loss? If so, that will interfere with the process.
Culture, gender, learned personality styles, and past history all affect how a person grieves. For example, if you believe that it is a weakness to cry or show emotion, your expression of grief will be severely inhibited.
Do you have a good support system? Having little or no social support makes healing very difficult.
How the person died will affect you—was it expected? Sudden? Violent? Some deaths leave you traumatized, while others may bring relief.
Finally, and most important, what was the nature of the relationship that was lost? Was it your child or a colleague at work? How you felt about the person, who they were for you, and how often you saw them all affect how you experience the loss.