Fe/Fi = ethics
Te/Ti = logic
The introverted side of thinking and feeling (Ti or Fi) are based on thorough internal independent analysis. They are very sophisticated and personal to the subject, therefore they are subjective. Example: Fi user determines ethics independently and isn't easily swayed by outside influences. Ti user determines logic (facts) independently and isn't easily swayed by outside influences. BOTH consider external influences, but ultimately subjectively have the final say and are willing to be the lone person with a perspective in a group.
The Fe/Te side is influenced by external factors. For Fe, their ethics are influenced by the group and they are willing to bend a bit if it keeps harmony in tact within the group. Te respects systems and values what is measurable as fact or useful (think the scientific method or following the function descriptions as close as possible without debating possible interpretations - less "wiggle room" than Ti). Te likes efficiency and order and action.
Also, because the introverted functions are so personal and important, it tends to take people longer to make a decision using these. The extroverted functions are usually more rapid as there is less internal analysis or "checking in" that needs to be done.
Leaving aside the problem that this description isn't something I personally can't get on board with: *if* the premise that IxFJs should 'use more Fe' to get out of introverting too much is to be believed then, by deduction, an INFJ who is sorta "NiTi looping"/caught on something should inculcate external ethics into their internal framework at a faster pace (or something)?
"NiTi looping" happens because there's something going on in the external world that an INFJ can't get on board with in the first place. While INFJs do often try to force themselves to put their own objections/complaints
on hold until they can effectively articulate why something is a bad idea (hoping some argument will slide into focus that will get others on board with their objections/complaints) - which is precisely the stuff "NiTi looping" is made of, 'bending' as a sort of placeholder while they wait for their objections to become clear enough to articulate - the way out of that definitely, definitely isn't more bending.
[And more re: op]
While I think one of the ways any kind of external influence can help with the "NiTi looping" is for someone who is capable of listening really well *and* who understands provides a medium for the INFJ to put their thoughts/impressions into language, so that they can finally let go of the information that's caught on 'repeat' in their head. But people who are capable of listening well and/or who understand are actually quite difficult to find, *and* I suspect there isn't a fussier bunch of people in this world than INFJs when it comes to needing both those qualities. Bouncing the looping ideas/impressions off someone whose reaction will only
add to the information that's stuck bouncing around inside - instead of providing a neutral sounding board that helps get rid of that internal confusion - is the worst. It's seriously the worst. Especially when I was younger, I'd internalize the fault whenever this happened, thinking, "what's wrong with me, that this person's advice/help doesn't work for me?" At this point I think I see it more for what it is (no one's fault, just a really fussy operating system) and steer clear of/maintain emotional distance to people who systematically make 'looping' worse.
And sometimes even someone who is capable of listening really well can't 'get through' - because ultimately the problem is more about (as lexicon mentioned) getting to understand oneself better, cultivating an awareness of one's needs and cultivating a firm sense of boundaries.