Times have changed a lot since your mom was a teenager. The trend for younger teens is to date in a group setting rather than one-on-one. If your mom is not even comfortable with such group dates, however, you might be able to get her approval by talking to her and letting her learn more about your girlfriend. Ask your mom why she doesn't want you to hang out with your girlfriend. Does she feel the relationship is inappropriate or unhealthy?
Agreed Right. He sweeps you off your cynical feet with nice dinners, roses, thoughtful gestures. The sex is absurd. You want to introduce him en route for your mom.