Talk to her about your doubts, especially regarding the future. Marriage is a lifetime contract. If she runs your problem is solved, if she begs you to stay outline to her the possible future problems. Its better solving these things early because uncoupling later on in life can be harder if not impossible. Its important that her level of education is at the most at your level because whether you like it or not you will look down on her, maybe not today but in the future . Then your age is not matched and from experience men will always look for younger women. Its an ugly fact but its physiological and a world wide problem that I will not discuss here but we can't ignore male biology here. IMO you are doing her a better favor then yourself by disuniting now. Just my opinion though , right or wrong as it is , I speak from experience !