Gnostically, you could even say that the continued rumbling relationship issues with Martha and Jack represent a sort of attempt by the narrative itself -- the universe -- to get the Doctor to remember, or admit, that both trees and forest are equally important, so that when the time comes, he'll make the right decision. Because no matter what, it's obvious that the Doctor's being silly, if not dangerously weak, in thinking that he can just stuff his emotions away -- like the Rachnoss and the Witches, primal aspects from eons ago, that he assumes have been cast out of the Universe. ("What happens when you repress something?" It goes away? "It comes back all crazy and pissed off!")
The sign at the Elephant, the inn where William's staying, doesn't portray an elephant, because nobody knows what an elephant looks like. It's a creature out of legend, like a Time Lord, or a buffalo. William falls in love with Martha, and the Doctor falls in love with William, who can see right through the slightly psychic paper: the Doctor wants to be known, but only with half his hearts. When Martha and the Doctor lie in bed together, the Doctor talks about Rose. Needless to say, this is gross for Martha, because she's crushing pretty hardcore, as anybody would. But there's another secret here, another hymn: once the princess's father dies, once she goes away to become a queen, once all Love's Labours have been Lost, somebody has to bear witness. The first stage of love is magic: the person glows, has superpowers, needs rescuing -- these are just the ways we put them in our story, the story we're telling about the things we need out of them that don't exist anywhere outside our heads. The first stage of love is this: so much energy on our side of the line that we can't tell where our fantasy ends and the person starts. She thinks she's in love with the Doctor, but she doesn't even know him yet. Not even the Carrionite witch Lilith can discern the Doctor's true name (although "Rose" comes close). Whether that's even possible, or advisable, is another question entirely, but it runs counter to the whole venture to answer it. The loop is closed in the final scenes of the season, when Martha accuses the Doctor of not seeing things right in front of his eyes -- which is exactly his complaint about Donna. In this way they are obverse reflections of each other.