At first, I thought Sarah was being cruel, insisting that Michael go see Sydney and say their goodbyes. But in the end, what it really said to Sarah was that he was saying his goodbye to her. If he had really loved his wife, he would've assured her that there was no need to see Sdyney, because he had her in his life. But Vaughn went, proving to Sarah that he needed to see the woman he loved. Sarah, obviously knew how things would end and she didn't want to hear the words that he was leaving her. Sarah ended up saying the words first.
Chris