There was a girl attending school with our hero. She left to continue her studies elsewhere; he had a bit of a crush on her, and misses her.
The plot throws them together again.
By the end, he concludes that absence made his heart grow fonder than the object merited.
BUT, to get this to all go, I have to depict her in a way that makes her initial attractiveness clear, and her hidden flaws. And when a good bit of it was backstory. . . .