Chastity isn't overpowered all the time, but in the right hands it's very strong. I think there should be some kind of counter for the spell. Casting MV on kd-mates who have it is not a good enuf measure. So, my suggestion is that when Love and Peace is active, that province is immune to Chastity. This allows opponents to still put the spell on certain provinces (MV + Chast) but prevents them from spamming a whole kd with spell.