Did you give your guy a magic mirror? If so, that means he was swapped to a girl. Im assuming the "new option" was a female sign going into a male one. That would mean you also gave the girl a magic eggplant. The eggplant would give the girl a dick, allowing her to fuck you, and the magic mirror would allow you to become pregnant. If you are sure you did neither of those then yeah, its a bug, but first check, since you seem to not have known that either of those items effects were possible.