HI MaryJane, discernment can be eveything as has already been stated. You say this person is
"unwilling at times to even extend themselves to family around them, even their own spouse or children?"
I have known some wonderful introrverts. When they are engaged, they can still be warm and loving and Christlike. They just do not care to engage or have to pull back after engagements and re-focus. That is one thing. Another is the man(typically the man, but not always) who is "unable," as opposed to unwilling, to engage his wife or children, never mind a wider circle.
Now this man's problem lies in his heart. It can typically(not always) be traced back to the childhood and the way he himself was raised. Its almost like a gererational curse(not overly comfortable with that phrase but it may work here)
The answer, as always, is engagement with God the Father through Christ the Son. Now, for the pesron involved, there must be a desire on some level to want to change, an acknowledgement of this behaviour. If the person refuses to talk about or acknowledge the behaviour(this frequently happens) then , as always, we must pray.
These matters of the heart, go straight to the heart of people. It shapes them, it shapes the children they raise, it shapes the relationship they have with their spouse, it shapes everything around them. Yet, the problem lies in reaching them, for often they have a gruff or stony exterior that frightens most away.
Yet only those with the eyes of the lord can truly see that these people are in many ways chained, and are, at their core, extremly vulnerable and sensitive, which is why they cover it up with the opposite behaviour. The Lord wants and desires to set these people free. Sactification is a process for all of God's children.............Frank