I remember watching the start of a film when I was a child, in the sixties and seventies, about a couple who met where he was a older that her, I think she was a young teenager. She wanted to grow up so that she could be have a relationship with him. The next time they met, she had grown up a lot and was more like a young women. At this point I had to go to bed. I have always wondered what this film was called and I would love to see it in it's entirety. I've no idea what year it was made.

Maybe Portrait of Jennie (http://en.wikipedia.org/wiki/Portrait_of_Jennie)?