If I were to guess the ending, it would be something along the lines that Ethan fights a few more Dominas and Rose and at the last stage, when he defeats the final villain, Master Roman (maybe the name's wrong) comes and meets him. Ethan thinks he has freed him and his friends (as for Rose, you can say Roxy is just hypnotised Rose or maybe fake Rose). But then the Master tells him that all this was just a way to train him so that he becomes capable of evading his weaknesses and compulsions, and learns how to win over them, and knows how to even fight his friends when the time calls for it.
How is this one?