In my experience disagreements between NTs and NFs usually arise from some sort of communication problems or misunderstanding. The NF usually looks for emotional motives in most things and will then take offense accordingly where as the NT usually tries to rationalise things and draws a blank when the NFs behaviour makes no rational sense... the two get together the NT argues in terms of logic and the NF argues in terms of emotions hence they are arguing in different languages and both end up with ess clarity than when they started!

On saying this I usually get on with NT amazingly well and I adore most of the ones in my life!