I'm making a (big) deal out of my girlfriend because she mixed spicy chips with dessert snacks
Why are you making a fuss about snacks?
Because I like non spicy snacks and I don't like mixing them with the spicy ones
How your gf presents snacks is a trivial matter in the grand scheme of things and you making a big deal about it is a hamper on your relationship. Let go of your small prejudices for the sake of your relationship.
You're right. I will just not eat them.
Great! It's good to hear that you decided not to let the snacks get in the way of your relationship.