<human>: Can you give me a shortened version of the text?

My girlfriend and I have a fairly decent, average, relationship with about one exception. Her manners are so bad that I'm embarrassed every time we eat with friends/family and I'm starting to get frustrated even when it's just her and I to the point where I have a hard time being "normal" around her eating. 

I'm not a picky person by any means and in general am very tolerant of people who don't do things "my way" but after three years of listening to her chew with her mouth open, bite her fork/spoon when she takes a bite, play with her food, and shovel it into her mouth bit by bit I'm about at my wits end. I certainly don't expect royal manners or anything of that variety but I am slowly realizing that general manners are a must in my relationship. 

I know the old adage of "just talk to her" (we really do talk about almost everything, very open) but I have a particularly hard time, I think, because I feel like it's not my responsibility to coach her in proper social manners. It feels a bit father-like and I get the "its not my job to teach her manners" every time I consider talking about it. It's the details that get to me, is it best to try and train her in every nuance that makes up good manners ("don't bite your fork, don't chew with your mouth open, don't pick at your food with your fingers") or should I just generally say "you need to work on your manners" and hope that she gets it? 
It's not just her eating habits, she seems to have been taught very few social manners but I thought it best to start here and see if I can figure out an easy way to approach such a topic.
<bot>: Girlfriend and I have a fairly healthy relationship but she lacks very basic manners and it's really starting to get to me. I have no idea how to successfully approach her and discuss it because I feel strange taking that role.