Well Roy and Starfire have already been together now so I don't really see much of a problem if a writer wants to pair up Dick and Donna now. They don't have the problem with sleeping with a "friend's" ex since Roy didn't give a **** about it. Don't think there are really anything standing in their way. Dick would be miles better than Roy at least for Donna, but it would at least be nice for them to be friends first again. They haven't really interacted much yet.
I'd like to see Dick and Donna at least have one conversation between each other before she goes off and gets to know Jason. Dick and her haven't really even interacted since she has been back.