When an ESFP finds the perfect balance between being slutty (Se) and being moral (healthy aux Fi development):

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When an ESFP finds the perfect balance between being slutty (Se) and being moral (healthy aux Fi development):
Dear ENFP, don’t pick the path of least resistance. It will cause you misery.
ENFPs' use of aux Fi
(This is by no means comprehensive, just some things I've noticed personally.)
Like all aux functions, Fi acts as a balancing force against the powerful dominant function, but it also serves it. (I'll get to what I mean by "serving" it in a sec.)
NeFi makes ENFPs highly people-oriented. Ne likes external validation for its ideas, and Fi desires emotional connections. High Fi, yes, makes them sensitive (both in the sense of being easily hurt, but also in the sense of being aware of how others feel/how they affect that.) It also makes them empathetic when healthy, able to put themselves in others' shoes. NeFi works well to draw disparate connections between experiences to gain a sense of understanding of what someone's experienced, though it doesn't always work out.
Now, when I say Fi serves Ne:
An ENFP's more free (not guaranteed, but in my experience) with emotional information, and to an extent, their feelings, if it will serve or further Ne's desire for external validation and more people to bounce ideas off of.
NeFi also gives them excellent propensity for people skills. Ne's good at reading between the lines, picking up on small things, guessing at what's happening, and Fi reads people's motives (though reading their actual feelings, however, can be tricky, and is ultimately guesswork based on external cues and/or prior precedent (Si.)
One downside (upside, sometimes, maybe) is that ENFPs can (and personally, often do) ignore Fi, in favor of more Ne fun, connection and external validation for its ideas. In my own life I have a tendency to avoid confronting my feelings until I can't anymore, or because I think figuring out what I want or acknowledging my feelings and taking action on them (Te) is too disruptive. The problem, however, is that Fi can only be ignored for so long. Things keep building and building until there's a meltdown... then it's usually okay, so long as you haven't stepped on anyone through a Te freakout.
So, a word to ENFPs: Take the time to value your Fi. Acknowledge it. Take time away to assess your feelings and be willing to ask for what you need from other people — if they're good to you, they will understand and try to meet those needs to the best of their ability. It won't disrupt your fun and idea-building — it may well make it better, since a stable relationship with a close bond lends to better understanding. Acknowledge it privately, too. Consider what you feel and why you feel it, and what you can do about that. Take the time to value your Fi. It is one of your most valuable assets and gives you special powers in understanding people, if you use it correctly.