An acquaintance of yours asks why you act so strangely around her. She seems a little hurt, and is worried you hate her or something. And the truth of the matter is that you have… well it wouldn’t be right to call it a crush, but you find her very beautiful and have been worried about making a fool of yourself. And it isn’t your intention to harass her or pursue her in any way, you’re not even looking for a relationship or anything right now, you’re just nervous around her for basically no reason, and she’s noticed and she wants to know if she’s done something to offend you.
What on earth is the correct thing to say?
This seems pretty great, and probably more than enough. I’d still like to bring extra options to the table, so:
You could also thank them for asking, to get some weirdness out of the way (you establish that you are happy that they are trying to figure out why there is any ‘weirdness’) You could also put some more emphasis on the fact that it’s internal and not triggered by something they could control in any way.
It can be nice to be in someones presence that’s so beautiful/attractive to you that it kind of makes you weird/glow/giddy/nervous :) . Not something we experience every day!