So a young boy falls in love with a couple of year older girl. Let say he is 13 and she is 15-17 years old. She might be a bit older, but it´s not a housewife with a boy.
I remember one scene where they sneak into a classical concert. A bit like she is showing him the grown up world.
If I would guess the age of the movie I would say between 1987-1991.