If you lie to your significant other, you will get caught. It might be minutes later, or it might be years later, but you will get caught. If you break up with them before you get caught, then you're good though. They can't get you anymore.
Cell phones changed the face of dating in many ways, especially in terms of espionage. You can be in two places at once. You can text that you're at church, but in reality you can be day drinking in a Target with your side piece. In this case, this unfortunate young man thought his girlfriend was home, so when he lied about being in bed, the last place he expected to find her was right behind him. I hope his next move was to stand completely still. Angry women are like T-Rexes. They can't see you if you don't move. They do, however, smell fear.