No one is indispensable to anyone else. You imagine you're necessary to him or that he will be very unhappy if you leave him, but I'm sure that if you do, within three months he will have fitted another face into your role and you'll see that no one is suffering because of your absence. You must feel free to do whatever feels best to you. Being someone's nurse is no way to live unless you're unable to do anything else. You have to say something on your own and you ought to be thinking, first and foremost, about that.