Peach and Siren

Ever since the start of the school year, Siren has this unexplainable irritating feeling towards her classmate, Peach. Peach is pretty and nice, she gets along with everyone,they don't have a grudge against each other either so why is it that every time she sees Peach she gets annoyed? Is it because of her rapid heartbeat whenever she's near or the unexplainable desire to hug and touch her?