I once read in David Keirsey's work that SPs don't like or don't care to talk about their inner lives, and that this will always create tension in NF-SP relationships.
Strangely enough, when I look back, I realize that as an INFX Healer/Counsellor, I've had tons of SPs (often the most extraverted popular types) coming to me for advice and sharing very personal things even if I barely knew them. I was always surprised to discover that inner life in them and to discover that they trusted me so easily. Then again, NFs are always everybody's psychologists, aren't they?
I suppose those were mostly SFPs. What do you SPs have to say about this? Certainly the ISFP has a rich inner life?