I'm on the Ishihara ship but tbh, either her or Satsuki ends up with mc is totally fine, as long as the story goes smoothly, and the ending is satisfying. Ishihara and Watari breaking up is fine and all, what's important is what will they learn from that, how the two can grow from their relationship, especially Ishihara. The only thing I don't like about her is her obsession, and if she can get rid of that, she will be a perfect girl to me.