This sort of reaction tells me that they're doing a good job with viewer immersion. People would definitely get separated in a zombie apocalypse and that is how you would feel.
With the addition of constant adrenaline and fear for your life and the lives of your compatriots.
Oh shit not Shane! He left Rick for Dead and fucked his wife, he's too nice a guy to turn into a walker in a field in a matter of like, less than a minute.