I'm guessing you and your friends are very young, low teens.
Hot girl, not hot girl, it shouldn't matter. You'll learn this when you're older.
The thing is, your friend the cheerleader is a big fish in a small pond right now, and that can be intimidating. If your friend the shy guy wants to date her then he has to learn to speak up for himself. Otherwise how will the date go, will he pass her notes because he's too shy to talk?
As for the meaning of aggravating;
ag·gra·vate (gr-vt)
tr.v. ag·gra·vat·ed, ag·gra·vat·ing, ag·gra·vates
1. To make worse or more troublesome.
2. To rouse to exasperation or anger; provoke. See Synonyms at annoy.
This is school, it will all change once it's over. The big fish cheerleader will become just another minnow in the ocean and then things will even out.
Even the "popular" girls don't stay popular forever.
