I totally know what you mean by the whole "holding back" thing. And in a sense I wish I was capable of something like that, like how some people wait until the day before marriage to say "I love you" and it actually MEANS SOMETHING!
But even then I think the dynamic works out between NFJ's and STP's. I find NFJ's seek verbal affirmation, and I am willing to give that. In fact I need to, or else it bottles up, which is painful to me.