The rule in American publications (the British are more sensible about this) is that when quoted material appears at the end of a phrase or sentence, the closing quotation mark goes outside the comma or period, like this,” rather than inside, like this”. The practice is patently illogical: the quotation marks enclose a part of the phrase or sentence, and the comma or period signals the end of that entire phrase or sentence, so putting the comma or period inside the quotation marks is like Superman’s famous wardrobe malfunction of wearing his underwear outside his pants. But long ago some American printer decided that the page looks prettier without all that unsightly white space above and to the left of a naked period or comma, and we have been living with the consequences ever since.

As Adam Freedman points out in his book on legalese, "What distinguishes legal boilerplate is its combination of archaic terminology and frenzied verbosity, as though it were written by a medieval scribe on crack."

[A] factoid floating around in the brain unlinked to anything else is as useless as a book filed on a random shelf in a library or a Web site with no links to it. This linking must be repeated with each sentence in the text. This is how the content of a passage of text becomes integrated into the reader's web of knowledge.

Word Frankenstein
Only Sense Allowed by Purists the fictional scientist
Sense Commonly Used If you insist on We’ve created a Frankenstein’s monster! you probably also popped champagne on Jan. 1, 2001, wondering where all the other revelers were. (“You see, there was no Year 0, so the third millennium really begins in 2001 …”) Give it up.

The main job of punctuation is to eliminate the ambiguities and garden paths that would mislead a reader if print consisted only of vowels, consonants, and spaces. Punctuation restores some of the prosody (melody, pausing, and stress) that is missing from print, and it provides hints about the invisible syntactic tree that determines a sentence’s meaning. As the T-shirt observes, punctuation matters: Let’s eat, Grandma has a different meaning from Let’s eat Grandma.

The problem for the writer is that punctuation indicates prosody in some places, syntax in others, and neither of them consistently anywhere. After centuries of chaos, the rules of punctuation began to settle down only a bit more than a century ago, and even today the rules differ on the two sides of the Atlantic and from one publication to another. The rules, moreover, are subject to changes in fashion, including an ongoing trend to reduce all punctuation to the bare minimum. They fill scores of pages in reference manuals, and no one but a professional copy editor knows them all. Even the sticklers can’t agree on how to stickle.

The disenchanted girlfriend, I surmise, is referring to three common errors with apostrophes. If I were her companion, I would advise her to consider which quality she values more in a soulmate, logic or literacy, because each of the errors is thoroughly systematic, albeit contrary to accepted usage.