If my girlfriend is a minor and she doesn’t want to end our relationship, what can I do?

I'm in a relationship with a 12 years old minor girl while I'm 22 I'm feeling so guilty but I tried to breakup with her two times but she loves me and not letting me breakup with her. Well it's just a social relationship, no sexual relationship or anything involved, I'm not breaking up with her because she is US citizen and have an innocent mind she would think about me that we are bad when she grow older. If I breakup with I'm so tensed my friends found it weird too, but I'm just thinking about her emotions, why is she not breaking up with me? Why does she still want to be in a relationship?