From a naturalistic perspective someone who has died is unaware that they are no longer alive, we the living are the ones who actually experience death. Even for those who believe in an afterlife, the death of a loved one still sentences the survivors to a lifetime without that significant relationship.
With the passing of someone we love we can no longer can share our thoughts, feelings, experiences, victories, or setbacks. We no longer have their guidance and support. Perhaps the biggest loss is the loss of a part of ourselves.
When we lose people who we have been close to part of us dies as well. Of all aspects of being human our identity is the least self-contained. We are ourselves, not only because of our thoughts and feelings, but also because of the way we experience ourselves reflecting back from the world which surrounds us. For a human even the loss of an inanimate object such as an address book, or a cell phone with a record of our communications, or a crash of our computer’s hard drive, can result in a significant diminution of ourselves. The loss of a friend, or an extended family member, has an even greater impact on the loss of our identity. And a close friend or family member, even more so.
Yet for all that is lost, as you become the sole custodian of all that was shared between you, the person you knew and loved does in a way become immortalized.