Well, depending on how far you've planned ahead and our current position in that plan, I'd suggest putting up a deadline for the frolicking, shipbound pair. Personally, I'd say, once the rest are making their way from the bar, or wherever in town they might be at that point, to the ship, the pair has to be done by or before [X] date, so the story can advance without hindrance. Of course, right now that isn't that much of an issue yet (right?).