>>6 Refusing to type anything that requires the shift key (and periods) is not a type of, "mistake." You didn't accidentally misspell something. You didn't forget a comma or period while rushing through a paper. Crisis isn't being a grammar nazi; he's being realistic. (Although he can be a serious ass sometimes, this isn't one of those times.)
You're not uneducated, though. You're just a lazy fuck who thinks that proper English should only be used in official paperwork -_- Anyway, that's enough of that topic.
Regarding the OP, if they don't like you, they don't like you. Don't try to force them to like you. What happens will happen. As a girl, I can say that I always listen to my friends when they say that a guy isn't worth it, and I hope she does the same. I doubt your girlfriend's friends dislike you for absolutely no reason.
Perhaps you should look for whatever faults you may have instead? It's kind of ass-y to want them to change their opinions of you without asking yourself what the actual problem is first.