When your girlfriend says, "There's no last train, so I'll go home by the first one (sob)," it might be a sign of cheating. For women, returning home in the morning entails risks far greater than men can imagine, considering personal grooming and timing. Being forced into such a situation usually means one of the three basic human desires—appetite, sleep, or sex—is overpowering. It's possible she chose to stay overnight while drunk, driven by the need to satisfy hunger or sleep.