Do murtagh and nasuada like each other?

Yes, of course, as in Eragon, when Eragon visits Murtagh, Murtagh starts to talk excitedly about Nasuada, praising her and admiring her. Eragon listens but with no particular intrest. I think that Murtagh and Nasuada fell in love or even kissed when she came to visit him in his room in Eragon, as when she left and told Eragon to go, she was really happy and dancing, saying that she had found it interesting visiting Murtagh and Mrtagh's attitude and behaviour was the same.