Really, this is just a matter of pragmatics. When one cares about resources and their allocation, it is important to keep the more important of resources safely stored away in the appropriate area. Such as Lancelot, in Susan's room. Susan is just being sensible, as always, to insist on appropriate resource management vis-a-vis gorgeous men who have sneaked right past her defenses and become precious important to her in unexpected ways. It's so logical it barely merits mention. She tucks her fingertips under the collar of his robe, stroking over the warm skin there.