Does it drive you nuts when your girlfriend chomps with her mouth open?

While i love my fiance very much and we normally get along well, something comes over me when she stuffs a handful of chips in her mouth (repeatedly) and proceeds to chomp and smack with her mouth open. My blood pressure skyrockets and i begin to understand the meaning of temporary insanity. It's like nails on a chalkboard to me and makes me want to rip my hair out! I tell her i know that i shouldn't be this affected by it but at the same time i am pretty sure that it is proper etiquette to close your ******* mouth while you chew.. Does this bother anyone else and how do you deal with it? Or am i just weird?..