I'm referring to the fact that it didn't take much psychological difficulties in offing a man's life - irregardless if he was going to live or not.

This is usually the psychological highlight of any zombie flick - because it actually takes a mental strain to those that are accustomed to the modern society when taking the life of a random person. That's pretty psychotic if you think about it (the lack of empathy and excessive self-preservation when said person committing the deed is not in the verge of death), unless they have been doing it for a very long while, considerably desensitized.

It is as if your characters are extremely methodical and cold, a trait seen very often in assassins/psychotic killers (not that I know of any really, based my assumptions on the run-of-the-mill assassins/psycho killer off pop culture portrayals lol), then flick back into normality as if it wasn't a big deal. (tbh what creeped me most was after offing a man still in his blood, the characters cuddled XD)

I would understand if the person turned, or has allowed it to happen. Even in latter cases as portrayed in zombie flicks - people were still squeamish about completing the act, even when the infected willingly offered to be offed in case they turn.

Gosh, I hope you get what I'm trying to say XD Words all jumbled up in the morning...

(edited several times cause I was afraid that I couldn't properly explain what I was trying to say lolol My command of English is kinda bad in the morning :X)