Clueless

should I dump my girlfriend of 3 years to go out with someone else?

Well if you're dumping her JUST to go out with someone else, then no. That's no reason. Because you might loose everything you've got with this girl (if all is going good), and the girl you're dumping her for might not be as great. And there's no turning back. She might take you back, but it's rare that she would, if you break up with her and a day later are going out with this other girl. It's a risk you can choose to take or not. I suggest you think this through. Do you really want to throw away 3 years of hard work?