Bilbo worried at this until he could not keep his eyes open, and had decided there was nothing he could say about Sara until Frodo was safe. He did not dare to risk angering Rory with tales of Sara, no matter how true, and he could not put his lad through more questioning, not now. Frodo did not need to be put through any more grief. He would talk to Rory alone. It made the most sense. With what I shall argue to Rory to make him relinquish Frodo to me, Frodo should not be there.