I don't see the part of the story where she is preventing his education. He responded himself by saying she wants him to get an education, she just doesn't want him to move to another town to do it which happens to be tied to a new person. As I understand, it was not his plan to go to that school at that time before the new girl came along. He wanted to marry this woman and was totally committed to her until he met a new person and she made him question what he was doing with his life. That sounds like NRE to me.
He says he planned to go to school all along but hasn't been moving forward with those plans while engaged. Is that really her fault? Ok so she gave him a job he doesn't need a car for and a place to live. That may have contented him into inaction. I'm sure there are students struggling with finding a job and paying for a place to live who might think that would take a lot of pressure off and make it easier to go to school.
I can see how you could be right about the older woman. I also see the OP saying repeatedly that he has been motivated to go to school by the new partner because she is going. That he wants to Sign up for classes with the new girl, move to her town and start his education and grow with her. The same way he moved to the other womans town, into her house, working for her business. Probably while he was in NRE. What happens when the new girl throws a wrench in? She drops out of school or they have an ugly break up. Now suddenly it's not so motivating to be in her town going to school with her. What if he meets someone else next week who has different ideas?
I'm not concerned about the NRE leading him to leave his existing partner for her sake as much as I am about it being what leads him in any direction. Of course he should go to school, that shouldn't be wrapped up in the relationship issues at all. Is the first partner preventing him from going to school or is the new partner just making going to school with her look really really good right now? Lets say we're both right and the older woman is not handling a relationship with a younger person appropriately and he's also being influenced by NRE with a new partner. I guess my advice remains the same. Go to school, be aware of influences, think for yourself, slow down on the lifelong commitments.