Zombie Cliché Lookout:
In a survival situation, you don’t have a whole lot of time for dealing with emotions or properly mourning the loss of friends and family. In a zombie survival situation, this is complicated further by the fact that the dearly departed will be getting up shortly to try to kill and eat you.
In most zombie stories there are usually characters who can’t quite put their emotions behind them fast enough. Luckily for them, there are also pragmatic characters who spout tough guy dialog like “We’re going to be dead too if you don’t get your ass in gear”. It’s a sort of zombie survival yin-yang thing.