Complex sentence: Hearing the teenage boy's thoughts about hating the music and wanting to leave town, she says out loud to make sure to get out before it's too late, because every year he waits, he'll just get more and more stuck here.
Split into simpler sentences: Hearing the teenage boy's thoughts about hating the music and wanting to leave town, she says out loud to make sure he does, before it's too late. Because every year he waits, he'll just get more and more stuck here.