Cavaliers do have ideal temperaments, It is not fair to take isolated cases and suggest it's becoming the norm. I have had the same dogs that one day will will stick up for themselves, and the next day will roll over and play dead; though none have ever got as far as fighting.

We probably all can react to a similar situation differently on different occasions, depending on our mood, if we have a headache, or are tired and irritable. Afterwards we wonder why we behaved in that way. Dogs are prbably not too dissimilar,