If someone says no to being asked to a dance, does it mean they're just not interested in the dance, or does it mean they don't like me?

Well, he may have had other plans with someone else. I think he would probably get from that that you're interested, so if you make it clear enough at least he knows that's a possibility. Can be a bit weird to keep a friendship going with a crush, and painful sometimes.

When I was in high school, if a girl that I liked, even one that I was head over heals in love with, asked me to homecoming or any other dance, I would have said no out of sheer shyness.

Try asking him to dinner or a movie, or bowling, or dinner at your home, or anything that is not around other students from your school. See how he responds to that.

Did he not go to homecoming then? Did you?

At my school there were the "homecoming" students and the very clearly "not homecoming" students. I was one of the later. And a guy I was dating took someone else to the dance and took me to the all night party and we were all fine with it.. I think.. I never asked the gal he took to homecoming how she felt about the fact that she went to homecoming with a guy who'd been taking me out every Fri and Sat. for a year. I suspect she liked him and he liked her enough to take her to homecoming. High school isn't really the place to shop for a spouse but it's a good place to learn to date and be comfortable around members of the opposite sex.

The thing is, what can mean a lot to one person often doesn't mean so much to some other person. Asking us to tell you what a fellow that you see and speak with often but apparently never discussed this with (!) isn't about him at all. If the two of you have never spoken about it since last fall it seems clear you aren't dating.

I think he had plans as he said. If he were interested in dating you, he'd let you know. You're friends only, I'm sorry.