Because we see her getting shot, but there is no funeral afterwards and nobody talks about her. And why do Kelsons girlfriend and Maya talk peacefully and the next minute she points a gun at Maya?? And why does Kelson think its okay that his brother kills John Townsend?? He could have just held him down. He didn`t have to break his neck.
sharethe girlfriend was in on everything with the cult of people at the end of the movie.
i doubt peter cared about john townsend after john tried killing peter. the brother reacted in defense for peter.
IMO:
Does Kelsons girlfriend die?
Yes. The bullet went through his body, nobody talks because that sequence was almost in real time, they probably didn't knew she was kill, but if you remember, when Peter shots his uncle, nobody in the church cares.
The girlfriend talks peacefully with Maya because at this point nobody she din't knew Peter realized about the pentacle. Also, i don't think Peter cares too much about what happened to the man who seconds earlier tried to kill him. in fact, he probably thought that his brother react in the heat of the moment.
Prostitute: What the *beep* are you doing?
Johnny: I'm gonna kill a bunch of people.