Well, Rimmer, ol' boy (you don't mind if I call you Rimmer, do you?), here's what Freud would have said. And, remember, even a broken clock is right twice a day.
You did not leave your keys in the car accidentally. You meant to leave the keys in the car, and you chose to do so with the car running in order to punish yourself as severely as possible.
Do you think it's just an accident that you were at this one particular spot in the entire universe when this happened? It pretty much came down the way you wanted, except that you secretly wanted your mother to pull your pants down and spank you, right there in the parking lot.
This, and only this, would have eased your tortured conscience concerning the girl in episode one of this sordid tale.