"Tom felt completely comfortable, as he had never felt at any party that he could remember"

A quote from the book that struck me as interesting was, “Tom felt completely comfortable, as he had never felt at any party that he could remember”. This is from the scene where Tom attends a party in Rome as Dickie Greenleaf. How can someone feel so comfortable when they are not acting as themselves? The person we know best is ourselves. He is living a life that he has never lived before. How can that be comforting? Much of his “comfort” has to deal with the fact that he is enjoying luxury that he has never had. It would be comforting to not have to worry about money and to be able to fancy parties every night, yet how could you feel comfortable when you have just committed murder and our wrapped around a string of lies? The fact that Tom is comfortable with the life of lies he is living only gives more evidence that there is something not right with Tom Ripley.