what happens when your someone...dies?
I can't speak to that, and I honestly can't even really imagine what that's like. But in terms of finding someone else, I think most people believe that there are multiple people that you are compatible with. Not saying that you need to immediately go find someone else, just that if it's desired, it's probably possible.
Maybe I'm just too heavily influenced by Sleepless in Seattle since I watched that last week.