She's not a Lady, Not too Yours Either

If a woman is categorized even as partially bitchy it means that she possesses such character features which prevent us from calling her a lady. She is insolent and capricious, she doesn't really care if she swears in the street on some jerk who spoiled her dress by falling in the puddle, or at a glamorous business party at her boyfriend's company when his main partner's wife called he charismatic (the bitchy non-lady wasn't well-aware of the meaning of this flattering compliment, she just judged a 'book' by its audible cover).
That makes us arrive at a conclusion that the bitchy lady's manners are not too perfect. She might now how polite people must behave among the cream of society or elsewhere, however, she just doesn't give a damn about all these idiotic formalities. She's tired of all those polite chicks that smiled at her and then attempted to stab her in the back when she was in college, now she thinks that it's much better to stab harder but without any hypocrisy or false forced smiles – metaphorically speaking in most cases.
Needless to say that your bitchy nymphomaniac may cherish her mind, heart and body solely for you. Of course, she most probably tells you little white lies about you being her one and only man, however, you have no clue about the fact that your one-and-onliness is successfully cheated on once in a while (if not frequently). It's not that it's that bad, it's just that this woman is wired this way, your inability to see it is the matter of your own concern.