I'm working on a novel in which a guy falls in love with a girl, but she is in love with his best friend. The good friend that he is, he steps aside while the girl and his buddy develop their relationship. About six months in the friend is killed by a gang of terrorists from Canada, and it is revealed that he is sown some top secret international secrets in the purse of the girl. So the original guy has to help the girl he loves, who is grieving for his dead buddy, survive constant attacks by Canadian terrorists. Meanwhile they are trying to track down a scientist who will help them get the secrets in the proper hands. When they finally find him he has just finished building a time machine. He is shot in a shootout and the guy and the girl try to set up the machine. She decides she'd like to go back to before the guy's buddy is killed, and he agrees because he so selflessly loves her. But a malfunction happens, and they end up going back to prehistoric times. Long story short, they eventually fall in love and start the human race. They are, indeed, Adam and Eve.