Well, 'The Little Princess' is a great one. It has a touching story of a young girl's experiences and friendships.
You should check out 'Bridge to Terabithia'. It's a beautiful film about the friendship and love that develops between two kids. The story is very emotional and the acting is top-notch.
I'd recommend 'E.T. the Extra-Terrestrial'. It's not a typical love story but has elements of a deep connection and affection between a child and an alien that's quite heartwarming. The special effects and the story are both amazing.