A bisexual rugby player allows me to expose his secret to his girlfriend who is unaware of his submissive desires

I stumbled upon a tantalizing secret while hanging out with my buddy, a rugged rugby player who's also into the military. He's got a girlfriend, a sweet little thing, but it turns out he's into some wild shit. He's got a thing for being dominated, and when I hinted at it, he didn't shy away. He let me play with his toys, teasing him until he was on the edge, then I brought out the big gun - a dildo. His girlfriend walked in just as I was about to plunge it into him, and the sight of me, a bisexual guy, about to fuck her man, was too much for her. She's not into guys, but she's into the idea of her man being fucked by another guy. It was a wild cuckold fantasy come to life, and I couldn't resist.