Martha is running from where she left Layla and Lucas with that Wyatt person, towards the object of her distraction. Jack, with a bundle in his hands. She’s closer than before when the Doctor joins him, and her happiness at seeing them alive is short-lived when she realises that she doesn’t see Rose, hasn’t seen Rose. She slows down a bit, thrown off by that revelation, and stops less than a few feet away when the Doctor uncovers what Jack is holding, revealing…
Oh God.
That’s the first thing she thinks, somehow unable to move as she realises that Rose is dead, that she's dead and that the Doctor and Jack are in so much pain right now, oblivious to anything but their grief. She feels a bit oblivious herself. She doesn’t even think about the clothes she left with Layla, or the fact that she’s close to shivering, because right now, it couldn’t matter less. She’d liked Rose. Rose could’ve been a good friend to her. Rose had started to feel like a friend to her. But she’s dead now. Does what could have been even matter any more once a person dies?
Slowly, as if wading through something thick, and feeling like she’s watching through someone else’s eyes, she finishes the last few feet separating her from the mourning men. She stands there for a moment, but doesn’t say anything. There’s a time when she should, and a time when she shouldn’t, and right now she knows (because she knows them), is definitely a time when she should just be and not say.
She sinks to her knees by the two, but doesn’t interfere.