Blame the English language for having one word to represent a spectrum of meanings far larger than the electromagnetic. Plus, kinda unfair to say they never interacted. The fact they went out of their ways to see each other and say hello every morning carries a lot of meaning.
The hello that was shown here was the first time they've said hello to each other though. "That's the first time I've heard her voice." Also on the same way on her way home she saw her with her brother. I'm not disagreeing with you, only pointing out that one of your 'reasons' is not correct :]
No, you're right. But there's a lot that can be communicated without saying anything specifically. So you're right that I was wrong with what I said, but again, they had plenty of times they did interact, even if it was only a glance in passing. I mean shoot, that's how most relationships started in medieval Europe, and even during older eras in Japan and China.
But my main point is that their "love" is a different kind of love than one shared by best friends who have known each other for a long time and then start dating. It's a bit more shallow, and has a lot of need to grow, but it does not make it nonexistent.