Why do Christians grieve so when a loved one dies? Do they grieve as much as an atheist? They'll be reunited with them in paradise so why so sad?

Surely it would just be the sadness of a loved one moving away or something right?

I don't mean this antagonistically and i apologize if this is insensitive. I'm just curious because it seems given the worldview that a Christian shouldn't be terribly upset when a family member dies.