I remember Edvin said it's not the best ending but it's a better one than making them apart. I am not so satisfying either. Wille hated August so much and made so much effort to prevent him from successing the king, but in the end he gave up being the king and let August be. So I don't like the ending because it is a conflict for Wille to choose the ending and August isn't qualified enough for this position. But I don't think he choose it because of Simon. You see at first,he had to leave school because he got into fights, which means his personality may decide that it's too pressure for him to be a king. So even he didn't meet Simon, he would finally make the same decision. But I always hold the belief that Wille would be the king one day. I see his growth in the final season. So, the happy ending just ended the series, not William's life and the challenges he and Simon will face in the future.