Clearly, I am no professional counselor or therapist.
Hopefully, this helps you to analyze yourself. I can conjecture but cannot tell you why you fell what you feel. That is a question only you can answer.
First, it is important to note that people do not handle death the same way. Some grieve openly by crying. Some feel nothing initially. Both responses are normal.
When you feel nothing, it could just be shock. See how you feel in a few day's time.
I would suggest you consider the real value of that friendship before worrying about your reaction to the loss of it. Is this a good friend you would have done anything for or an acquaintance whose company amused you for a time? Do you see where I am going? If it wasn't a strong friendship, what real loss did you experience? If it was a minimal loss, why, then, should you grieve?
If you're worried about not grieving because of some Locke-ian sort of motivation (as in "Do not ask for whom the bell tolls, it tolls for thee.") consider that you are young enough to miss the meaning in that statement, and it is OK. Maturity and wisdom come not only from surviving your youth and aging, but also from actively exploring the meaning behind what you encounter. Every one matures at a different rate. Every one gains a different level of wisdom throughout his/her life's journey.
I should probably go do laundry because I seem to contain no answers today. That might be a more productive use of my time. :D
On another topic, thanks to everyone here on the Forum for taking my request to heart and helping to change the focus here from what psychopaths imagine about themselves and what non-psychopaths imagine about psychopaths. This has improved things greatly.
I am pleased also to see less flaming, fewer foolish arguments. I am beginning to see more mutual appreciation and mutual explorations in depth. Civility is the basis for any meaningful conversation.
All of us need to be seen, heard, and understood, and I hope this Forum will continue to evolve into a good place to give and receive that kind of understanding.