Basic idea is that girl has a boyfriend maybe even husband but no sex yet. Doesn't matter much why... Maybe they believe in waiting for marriage and the guy messes up partying and getting too drunk, maybe they haven't been together that long yet, or maybe they do some light petting over the clothes but never further than that getting each other hot and bothered.
Then some other guy takes her without him ever knowing. I would also prefer if it was unprotected sex for the heat of the moment, or maybe the guy lies and says he is sterile or something.
Then some other guy takes her without him ever knowing. I would also prefer if it was unprotected sex for the heat of the moment, or maybe the guy lies and says he is sterile or something.