I would still contest that Kiyohime shouldn't be romanced. I mean, she sees you as Anchin, not as yourself. So the one she loves isn't YOU. And also if you look into her story, shes.... a bit young.
Let me guess: her love is so high that it can't fit in the meter, causing it to crack open and fall out because of the pressure of it all
Edit:only had to read one more page to confirm it.