If your girlfriend says, "I missed the last train so I'm going home on the first train (crying)," it's a sign she's cheating. She's definitely cheating. This is because women face a much greater risk of coming home in the morning than men due to the need to look after themselves. The reason she goes home in the morning even at the expense of her health is one of the three major desires: food, sleep, or sex. Would a drunk girlfriend come home in the morning to satisfy her food and sleep needs?