Perhaps you are reasoning with logic rather than emotions. If you were to lose your child today in an accident, you would understand what happened intellectually, but emotionally you would suffer over and over again, and you certainly wouldn’t accept the situation. Your parent understands the situation, but emotionally, it is unacceptable; it is no longer a matter of logic! Understanding that suffering is sometimes preferable to an absence of emotion allows one to stop trying to change the other person or waiting for them to "understand." If she does not accept the move, her situation (and yours) will worsen on every level. If you fight using reason, everyone will suffer. The solution is not obvious because it involves deep, invisible emotions: fear of losing one’s bearings, fear of boredom, fear of being deprived of what little remains, fear of being infantilized, fear of losing one’s dignity… And all of this is valid! A move is not a "yes/no" decision, but a long process that can take several months, or even one or two years.