My Wife Went Out, So Who's the Person in Front of Me?

Late at night, my wife wasn't home. My phone rang. It was a video from a childhood friend. I broke into a cold sweat. The woman in the video looked exactly like my wife. So who was the woman beside me? My wife suddenly leaned her head toward me. "What are you watching?" 1 I hurriedly shut my phone. "N-nothing." My wife punched me. "You heartless jerk! Just now, while we were making love, you said you'd give your life for me, and now you won't even let me look at your phone! Give it here!" I scrambled out of bed and switched on the light with a snap. My wife rubbed her eyes, a blush still on her face. "Lu Kai! What are you doing? Why'd you suddenly turn on the light?"