It might be the whole "offline for 3 months with a stranger" situation. How safe is that for anyone, free or not? Loving to teach is an imbalanced motive for the expense and solitary dedication. That's not a student. That's a disciple. The need to continually "add sugar until someone bites" just adds to the creep factor.

Your motives may be entirely pure, but this is a case where absolutely everybody in their right mind should look a gift horse in the mouth.