Yes, seriously. You actually don't have a clue in all honesty!!
I work for a very large organisation based in multiple occasions. I've come across situations where horseplay has either gone too far, or there's a falling out between two employees, and one then uses it as the basis of complaint about another. These people don't work in offices. We don't tend to find that sort of behaviour in office situations.
If Amanda was complaining every week and nothing was done - surely someone should be held responsible for that too?
However, there's a difference in him speaking inappropriately to be met with disapproval and disgust, and both of them exchanging inappropriate banter on equal terms. It sounds to me that the latter was probably the case, but when it all went sour she took umbrage with absolutely everything then.