***HELP!!!*** IS HE INNOCENT OR GUILTY?

At our school around valentines day we have really embarring serenades. Two girls who i thought were my friends and one other guy that they know were going to send me a serenade from the guy I like as a prank (thankfully, they didn't end up doing it). They are also really good friends with the guy I like. The guy I like started to change about two months before this. He used to be very mean to me (telling people I was annoying, making fun of me, and everyone said it was weird because he's always nice to everyone, even if he hates them), but now he is much nicer/flirtier around me (he always looks at me, only makes fun of me playfully and apologizes after, stands up for me when other make fun of me, helps me when I ask, etc.). So my question is, did my crush have anything to do with the prank, and was that why he changed (to fool me)? Or is he genuinely interested in me (because it really seemed like he was/is)? And what should I do about the two girls/this situation? Please help!!!