The thing is you can go east and find a cure for the illness as the first quest you undertake. There is no warning that this is the event that will lead to the end of act 2. I had done about 50% of the quests in act 2, and the illness one was just one on my list of things to do, then suddenly it's all over. This is really bad design, and very frustrating since there was a lot unexplored in the act for me.
