Yes, they have had other loves but I still think they WOULD look cute together. They might even bring something very positive to their tennis careers if they have a relationship that is more than friendship.
But like you said, Anna is with someone else. And although I heard that Sylvia and Marat broke up already, he might be sseing someone else. Yes, we should care more about their tennis.
But you have got to admit -- THEY DO LOOK CUTE TOGETHER. :)