Remus knew the difference between Regulus' smiles, though, and the subtle changes in tension only someone very familiar with having their hands on a person would notice. He wasn't sure exactly why, but he had the sudden impression that Regulus would rather Remus did fall into his own bed -- without Regulus.
And he really wasn't sure what he'd done this time, when they were just getting over one argument. But, it seemed 'I'll be here a little longer' now meant 'I'm leaving now'.
"All right," he said hesitantly, when the other man moved away. "If it's not going to take that long, I can wait, see what time you get back? Maybe we can both go to see the others later after we've had some time for us? Unless you'd rather spend the time in your research when you get back."
Remus regarded Regulus helplessly, not really sure if he should push or let it go until later. And he'd been looking forward to such a pleasant morning! "Would you rather I go to my own rooms?" he finally asked with a sigh, hoping the answer would be 'no', but afraid it was more likely to be 'yes'. "I seem incapable of doing anything but upset you this morning."