This girl I liked turned into a completely different person

It all started at the beginning of this school year where I met this girl who I thought was really pretty and cool so I tried talking to her and it was a little rocky at first, but eventually we hit it off. We are both trombones in the band (which is how I met her) and every game we'd sit next to each other and talk so much to the point where people genuinely thought we were dating. Now obviously I had feeling for her but I didn't want to mess things up so l decided to try and wait it out. Eventually we ended up at our winter concert and pretty much every night leading up to it we texted each other for a few hours until one of us fell asleep, but when we got to the concert week she started to become a completely different person. She was much ruder to me and whenever we were together for something she would put her headphones on and just ignore me. We would always tell each other anything we had on our minds and if we ever actually pissed each other off we would be well aware. now to this day she's still a shell of the girl I knew and i've since lost all those feelings I had for her.