Well, in fact, you don't need to defeat the Keepers of the ring to complete the quest of Rina. I tried to kill the miller and then go to the thieves guild, and I was able to remove the curse of Rina. But yeah, I have to say that the first time I did that, it was a little weird situation because the hero knew the magical words to remove the curse without having defeated the Keepers, and consequently without having spoken for the third time with the mages
