It could be their Ni. Ni wants to do things only if there is meaning to it. (Reason behind it.) As opposed to Ne, which wants to do things just for the idea of doing it itself. Maybe that's why Ni isn't as much fun as Ne . I could be wrong about the function theory I made. If it is correct I should point out that INTJs are Ni doms. So if she wants a relationship with you, it is genuine and she sees meaning behind it.