Just tell them that bitcoin works like a money, like other foreign currency, its just that bitcoin has more than 100% higher than the US dollar. That way I think she will have a second thought before ignoring bitcoin..
bitcoin is money, but in digital form, why do not you give a little bitcoin you have and teach him gambling or trading, perhaps he would be interested, other than that you can get closer to her 
Women don't need any motivation to use bitcoins, as women around me are fond of using credit cards and fiat for making purchases so I don't waste my time by recommending them to use bitcoins.