It strikes me that ENFPs are the one MBTI type that truly extroverts Fi. ESFPs are much more grounded with Se, while Ne for the ENFP seems
almost translucent, and that Fi element is there for all to see.
Thus in human interaction, ENFPs are naturally doing the one thing that every other type strives to avoid: reveal themselves. It is this self-revealing, expressing genuine interest towards others in an innocent way is what is easily misinterpreted as flirting or even romantic interest, especially if the ENFP is young and unpracticed, and the target is unusually shy and perhaps has never had a date. Being genuine in this manner is both a virtue and a curse. It is virtuous because it is honest, but it is a curse because real people (at the Fi level) are messy and it is easy for others to misunderstand what they see. What they see is everything, all the good and all the bad, the pleasant and the annoying, everything that makes up the person. Everyone is like this, inside, not just ENFPs. The ENFPs are the ones that habitually reveal it.
The negative reaction is that what is revealed, Fi-wise, contains very strong certainties with which others often disagree, and mostly unanswerable/unsolvable questions and problems that others interpret as requiring solution, even though no solution is required or even requested. We all have these certainties and questions, but most of us don't talk about them or reveal them, or resolve only to talk about such things philosophically. Fi, extroverted by Ne, abstracts them and broadcasts them, unvarnished.
INTJs seem to be the one type that usually reacts well to this unvarnished output: we INTJs cannot read people, but dang, we sure can read them ENFPs!
We are so happy to be able to understand another human being this clearly, we don't give a crap how messy it all is. In turn, the ENFPs gain a relief from their curse: someone around whom they can say anything without fear. Though, like the
Babel fish, pure honest communication can simply verify that two people really don't like each other at all.
As ENFPs gain experience, they learn how to control their self expression so as not to unduly swamp others with their Fi messes, not so much by trying to be more Fe or Te, but by refining their Fi understanding.