It's natural for PCs to do everything they can to look out for and help one another. But in real life people trust one another to go their separate ways and take care of themselves every day. Try doing that within a game some time.
(The difference of course is that in real life people don't go off to fight necromancers, or raid evil corporations in a neurally connected cyberspace for dirty secrets, or take on superpowered villains in city-crushing battles. Okay then, if you do this in a game, then you might have fellow PCs end up splattered all over the place. We never claimed the ideas we write here are necessarily good ideas!)
C-3PO: Excuse me, Captain Solo, has Luke reported in?
C-3PO: He's not back from his tauntaun patrol.
Han: Oh. Well. Didn't he report to you? He mumbled something about a protocol, and you're a protocol droid.
C-3PO: That's not what it means.
Han: I'm sure he'll be fine.
C-3PO: I know Luke. If he hasn't reported in, he's not fine. It's nearly night time, and—
Han: He'll show up.
C-3PO: He could be dead! And nobody would ever know for sure!
Han: I better go look for him! Chewie, fire up the Falcon!
Chewbacca: Oh. Would you prefer it to fall apart, explode, or merely melt into a puddle of goo? All three are equally likely in my considered opinion.
Han: <sigh> I'll take one of those won-tons.