Haha ok so the curse is that all the males of royal blood will die by the hands of their loved one if ever they love said person. Doesn't matter if it's romantic love, platonic love, or familial love. The only way for that curse to break is to have a female be birn into the royal family.
After a lot of generations without any females at all, Chloe is the first one to be born. So, now you can say that officially, the curse is broken. Or safe to say, from the moment that Chloe was born, the curse was already broken. The only reason why they all didn't know is that someone caused harm to her mother, causing her to run away (kidnapped?) from the palace. Nobody even know if she gave birth safely, the first bit of clue they got is what caused the crown prince to find her at the slaver's place.
As of right now, the three brothers are trying hard to keep her safe because people might still be trying to harm her. Currently, Chloe is the highest female with authority in the kingdom, making a lot of people want to take her place. Especially the mothers of the three princes, since they all are vying the position of the Queen. Since the curse was confirmed broken, they all want to be the Woman with the most power.
So that's the gist of it LoL
Are we just ignoring the fact that she is going to die for her brothers orrrrrrr, does my Crack brain not remember that correctly