It stems from the use of "obey" in the wedding vows of that generation, which only the bride had to say. It was taken as a given that if he wanted sex, she had to allow it. Slowly that vow is dying out, but there are some who still say it. Sadly this is very true. There was very little protection for women back then, and a closing of male ranks if women complained about assault. I don't think younger men today have a clue how bad it was.