Marriage isn't about 'right' and 'wrong'. But it is about treating the other person well, and about understanding that there are languages of love for both sexes. Maybe I have misunderstood the situation, but I thought that C's husband was engaged in [at least] and emotional affair with an OW, and looking at what C considered to be porn, and she felt hurt by this.
yes he was honest about the porn, but he isn't a puppy, and he is capable of understanding that being honest about something that the other finds hurtful doesn't dissipate the hurt. I understand the analogy, but marriage is between equals, not a puppy master relationship. Her h needs to help her to recover from the hurt by kindness and sensitivity.
So yes, one could argue rather fruitlessly about what constitutes porn, and point out that everyone has to make an effort in a marriage. However C's husband is doing things which many women would be understandably upset by.
I do know a little about the effects of pornography on relationships, I wish I didn't [And i am not talking about a few raunchy pictures here]. It has little or nothing to do with what is going on in the marital bedroom, and a great deal to do with issues relating to the one looking at porn.
The main point is that it is not c's 'fault' that her h is looking at porn, and to suggest that spicing things up in the bedroom will sort it out, is sadly, almost certainly incorrect.
It is great to get a male point of view, but please remember that women do feel things differently, and no renditions of 'Why can't a woman be more like a man' pleae!! We aren't, and I don't think you really want us to be.