Thin paperback book about a boy and his friend (a girl) who meet a woman in their community who is very mysterious. When her hair floats, magic is happening. Her name may have started with an M. She helps the boy who we find at the end had some family tragedy that he was blocking out. The woman helps him fly. She shows up when he needs her but sometimes he can’t find her.
Cover may have had a picture of the woman with her floating hair. It was probably published in the 60’s or 70’s and it might have been British.