Death is a difficult subject in writing. (It's a difficult subject in real life, too, but for different reasons.) It is a powerful experience, drenched in overwhelming emotions. I've covered the subject before, so I will jump straight to the new content.
Part of what makes death so powerful is that it means somebody is gone forever. Death is certainly the ultimate in gone forever, but it is not the only contender. When your friend moves to another state, she's gone forever. When your coworker gets fired from his job, he's gone forever. It's not as severe for death, but you aren't going to see them again. With technology, you can keep in touch, but it won't be in the same capacity.
When somebody is 'gone forever', you talk about them like they're dead. You miss them. You mourn their loss. You aren't quite sure what to do with yourself. The fact that you know they're not dead doesn't seem to take away the grief.
You can elicit a similar response in people that death does by finding some other way to make them gone forever. You have two examples from me, what else can you come up with?