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.:lol: Dogs are prbably not too dissimilar,
Our Sophie is the sweetest little dog and goes mad for people to pet her, when we're out walking. She has never been aggressive, lets me remove her food and rawhide chews, and is very patient.
However, she was Horrible Hostess this past weekend. Our son and his wife came for a visit with their 4-month old mixed-breed puppy that currently weighs 37 pounds (almost 17 kilos) and quite boisterous. Sophie didn't like having her own butt sniffed (but had no problem sniffing Belle's) nor did she like Belle bothering her by lunging for play or a sniff.
Our Sophie is not quite 2 years old, so still a puppy herself. At one point, Sophie snapped and growled at Belle and we were all quite surprised. Belle was not observing canine boundaries after 2 days, and possibly not recognizing that Sophie is dominant dog in her own house as far as this pup was concerned. The look of pure hate that our sweet (?) little Sophie was giving Belle, as she (sophie) sat across the room by herself, had us all giggling, but there you have it.