Suspecting my girlfriend was cheating, I asked a trusted junior colleague to test her and secretly watched them alone together. To my horror, Hinako gave him a lingering look and admitted she was sexually frustrated because she was not sleeping with me. I desperately signaled for him to stop, but he went along with her as things escalated. She stripped, sucked him, and fucked him while I could only watch the nightmare and miserably jerk off. Even when our eyes met, she ignored me and kept moaning through rough sex with him, proving that testing her had been my worst mistake.