why do you even want to tell her about bitcoin, she might think you are a nerd, haha. but seriously if you want to tell anybody about bitcoin it is better if they see you use bitcoin as a currency to purchase stuff, and showing them services like purse.io and all the discounts might help too.
LOl using bitcoin doesn't necessary tell you that you are a nerd. Maybe in some point the guy wanted to show off. Like saying that he is advance with other people because he is into some kind of tech trend. But at the end of the day I agree that it is much better to show her how you use bitcoin to pay for your dates
or for buying her a gift.