Once upon a time, isn't that how such stories begin? Something happened one time or a few times in that time? Something like that. But life got in the way, it happened before anyone could even realize aything was out of the normal.
Not everything has to make sense at the current moment in time. It can actually just be there when you least expect it. Nothing matters. Nothing has to matter. It can simply be what it is and you don't have to worry or think about any of it going on. So you deal with it.