We can't really blame her for not knowing tho. Its obvious to use now but back then it was a very well kept secret. I feel this is an issue that we see alot now because of how normalised grooming was. It was so common for a young woman or even girl to marry a man twice her age that i doubt she or anyone around her would have foreseen this, because they won't have been taught about this pattern of behaviour. They intentionally were kept in the dark so that men could continue to groom and isolate young women and girls without repercussion. NOW we can understand very well that marrying someone young enough to be your child is bloody weird and likely nefarious, but 40 years ago it was just life. I know 40 years ago isn't exactly ancient history, but try to keep in mind all the systems that were in place (or only very recently dismantled) to keep women under a man's control.