Your innocence and the way you see things are the only reason why you are in risk of getting killed. You only striked at and killed infected when needed, but never people that have the audacity to hurt you.

Things were a lot harder before you met Joel, but since you have met him and started some form of relationship, he's been protective of you as a friend (probably even more now). And once he heard some asshole attacked you, he was pissed

"That motherfucker... Where the hell are they?!"