[bryony]

I may be tactless, but, hopefully, speaking a few home truths just might spark some shame and a feeling of how the other person feels.

And shame is always so helpful. Its such a positive emotion, after all. (rolling eyes here.)

Yeah, rather like your comment. Clearly you are of the generation that thinks that, whatever you do, you should never feel shame. Charles Manson will be relieved.

If you really think cheating on a partner is ok, then we have nothing to discuss.