She runs several possible translations on that phrase and how he says it a few times. "I'll join you later, then." After he's fallen asleep? That might take a while, despite his obvious fatigue. "When I'm finished out here," she adds, choosing to stick to the obvious delimiter. Honesty. No second-guessing.
Except perhaps in the matter of sleepwear. She makes a mental note to change somewhere outside the bedroom, so as to avoid the suggestion of seduction.