I don't know if this would work out romantically in the long term, but for now it's a cute story of a boy having a crush / wanting to befriend a tiny classmate. I enjoyed it.
I wonder... if there was a wizard who could turn either the boy smaller or the girl bigger, which one would want to change size? I bet the girl, since she's in perpetual danger of being accidentally crushed. What if a human-sized desk tipped over and fell on her? I know she's tougher than she looks, but that would probably kill her.