How does the relationship between Langdon and Sophie change, in Chapters 79 through 84, and what events are foreshadowed that may cause them to have conflicting views?

While Teabing gives Remy directions to the church, Sophie and Langdon have a moment alone, in which she tells him how glad she is that he is with her. Langdon feels some attraction between them. Sophie goes on to ask Langdon his advice on what to do if they find the Sangreal documents. He does not want to influence her with his opinion, since it is clear that her grandfather had entrusted her with the secrets. This foreshadows the fact that the two of them may become romantically involved, as well as the fact that their views might conflict if they do find the Holy Grail.