Should i move to be with her? marry her?

Your questions are valid, and thoughtful ones. You may think that she is very mature for her age, but she is still a very young woman, and still forming her ideas of how her life should look. The fact that she is so willing to possibly throw away a promising career for marriage, and children, suggests that she hasn't really thought it all through. If she were closer to the end of her career it would make more sense. And she may say that she loves your kids, but she wants to uproot 2 children who have struggled, and move them away from the only family they have known. Women come and go, but they need their family more than they need a woman to sleep with dad. If you ask her to move and she does, you run the huge risk of being blamed later for the demise of her youthful opportunities. There is no need to rush into anything. Love survives the test of time. If she's still around in a few years, then you can revisit the matter. Do not confuse your desire for a female companion with the obligation to your children. Your family and children are far more important than your sex life.