"Fe seeks social connections and creates harmonious interactions through polite, considerate, and appropriate behavior. Fe responds to the explicit (and implicit) wants of others, and may even create an internal conflict between the subject’s own needs and the desire to meet the needs of others."
Essentially they're empathic and so move towards external harmony.
"Fi filters information based on interpretations of worth, forming judgments according to criteria that are often intangible. Fi constantly balances an internal set of values such as harmony and authenticity. Attuned to subtle distinctions, Fi innately senses what is true and what is false in a situation. With Fi as their dominant function, INFPs live primarily in a rich inner world of emotion."
Fi has more connection with internal emotion, sense of 'rightness' and 'wrongness' and yet also autheticity. A mixture between what's good (harmonious) and what's true, and real to ones innerself. ~Both quotes from wiki.
This confuses me a tad. I'm likely Fi, but it's not as if I'm masses amounts of volatile emotion; almost the opposite. My feelings only show their real, strong, true faces' occasionally. I introspect on happiness and contentedness too much to ever let myself believe there's much feeling in those concepts. The 'criteria' must be adhered to, and so it leaves me thinking things through, though not for Fe reasons(though now I say this...) - here's my guess at a distinction...
I must be 'good' because that's what feels 'right'.
I must be 'good' because of how others percieve (me)/will react (to me).
And, last wifflewaffle, I'm far too second guessing to know what's wrong or right...
*Is majorly going to bed now* Just putting some thoughts on the table.