The story I got is that he had a three year 'relationship' with her while he was married. Apparently, he has admitted to this, I guess. What he is denying is the 'sexual harassment' part of the allegation.
She claims that once the relationship ended, she was blackballed from Fox. That is the issue as I understand it, not the fact that they had sex. This seems to be undisputed.
We shall see. It should be mildly interesting to follow this for the next year or so. Unless they settle. Which Fox usually does.