I believe the main cause of the duke's proceedings was the poet's own violence of behaviour and incontinence of speech.

I know him well; there needs no other motive Than that most strange incontinence in crime Which haunts this Oswald.

Once more: English sentiment is such that the mere suspicion of incontinence on the part of a woman is enough to blight her life; but there are peoples whose sentiments entail no such effect, and, in some cases, a reverse effect is produced: "Unchastity is, with the Wetyaks, a virtue."