Thank you for summing that up so well.
The difficulty is that I am so pleased that he has done this the right way round in terms of expressing a need and telling me clearly what he wants that I really don't want to just say no.
I don't dislike the person, she seems quite nice but I know that she has some problems and while I feel for her I don't want to take responsibility for her vulnerability. My head knows that she is old enough and wise enough to make her own decisions but I can also see her vulnerability. It has taken me a while to become strong enough to express my own needs and I still 'wobble' a bit when I feel as if I am putting my own needs or wants before those of the people I love. Sorry, that last bit probably doesn't make sense.