Apparently, the person that I've fallen out with is unsocialised and a bad liar. Yes, this person took the old tale that lying is bad to the point were they think that even the "diplomatic white lies" are a sign of hypocracy.

Yes?? Then why is it that I have caught this person out in some real whoppers, and a discussion tonight has revealed that other people have caught the person out in equally big porkies too. Including the one where said person was telling everyone that the live in partner knew all about the affaires and didn't mind, when of course the opposite was true. Hell, I even provided alibis at one point and after the partner threw a wobbly over one "fling" I had to have the "lover" staying with me. I could cite more.

But tell me is this the behaviour of someone who is so taken with the idea that lying is bad that they cannot lie at all?

Nah, didn't think so.