Ah, but Nine has no compunction about lying to Rose, by omission or outright, when he's not willing to talk about something or when he thinks her safety or well-being are at stake. He lied by omission about regeneration; he lied by omission regarding the death of his people; he lied outright when he sent her away in the TARDIS in PotW. In this case, he lied because he'd have had to talk about his discussion with the Edanya, and he didn't really want to face what they'd said about his feelings for Rose. And he certainly didn't want her asking about them! And also, he's most concerned about her getting well, and he's afraid she might insist on going back. He doesn't want that.

Nine's a complicated Doctor to write, mostly because of his complicated emotions regarding Rose. I hope you can understand why I wrote it the way I di. :) Glad you enjoyed the rest of the story, at least!