Alright, stepping back and pretending that the OP is not an anon and can therefore have a girlfriend:
If your girlfriend was not into anime before she met you, give up on any hope that she ever will. Any interest you see grow in her will be the result her forcing herself to like your interests (feel flattered). She'll hate it, feel isolated when you talk about it around her/with friends, and women are horrible with that. It'd be easier for you to give up anime, but since that is not the case with anon, enjoy the breakup and your hand lotion.