It's hard to fake real emotions, particularly when the expected emotional response is complex or is unusual enough that you haven't had much experience witnessing it, much less practicing it well enough to be considered genuine. Better to instead come up with a lie about why you aren't having the expected emotional response. For instance, I had a close family member die. I didn't feel like making a big deal out of it but I also had to be out of town for a while, so I had to let some people know about it. Some were surprised that I didn't seem that upset. Luckily I had a readymade excuse: "It was expected. S/he had actually survived longer than we thought, so we are just grateful for the time that we did have with him/her." Voila. Death suddenly becomes something that you could legitimately take in stride.