making you a man does not mean TEACHING you how to be a man, which is what it appears you may have confused.
a person can be brought into ur life for a purpose said person is not even aware of. there are people out there who (given their unique life experiences, and their own unique personality) are the best tools to smooth out any rough edges you may have in your life.
u cant become smart about ur dealings with women UNTIL you've experienced things first hand OR you witness the experiences of others.
in the case of the OP, sure, its cool to chastise the girl and what not, but ud be doing urself a disservice is u refuse to find a lesson in the situation. She clearly has told you on more than one occasion that she got turned off by some things you did. You can take the easy way out and say "aaah shes bugging. somethings wrong wit her". Or, you can try to understand where she's coming from (not just as ur girlfriend, but as a person of a opposite sex, the female gender). If this girl says X/Y/Z turns her off, you can bet your last dollar there are many girls out there like that who get turned off easily by those same things. So in that sense, this girl is teaching you HOW NOT TO TURN HER OFF AGAIN.
ol girl coulda just hit him with the "hey, things arent working out. lets see other people" without giving any explanations. in which case, what would he have learned?