This is something to which @OrangeAppled alluded once and which I have been thinking about. I think I may also have read @Udog talk of something similar.
I think that the restrictive Fi Value is a belief that constrains Ne,or an aspect of Ne (i.e. one particular possiblity/outcome). It can be seen as an overriding construct which allows indulgent fantasy yet sabotages the outcomes before their mental and/or physical completion. Below are a couple of examples which I give within the context of a relationship, since this is something to which everyone can relate.
Ne: I like this new person/friend. S/he's very nice/funny/interesting/attractive. I enjoy being around him/her. I wonder what s/he enjoys? I'd like to spend more time with him/her to learn more.
Restrictive Fi Value: Is it wrong to like someone other than my partner? Where are the boundaries between like and love? What if I have transgressed those boundaries without even realising it? Would that make me a bad person? Am I being deceitful, or treacherous? I am too interested in this new friend; it simply cannot be a good thing.
Ne: Well, even though I've just come out of a relationship, and I felt bad for a while, there are other opportunities in life. I'm excited to think of new things. Maybe I might even meet someone new? I wonder what that would be like...
Restrictive Fi Value: Is it wrong to want to move on? What if I met someone and my ex didn't? I would feel bad because s/he would still be upset about the end of the relationship and I've just moved on. Would I feel guilty in enjoying myself? How can I legitimately enjoy myself when my relationship has just failed? I've haqve fallen short of perfection; it is wrong to revel in that.
You can see how overactive Fi is at work here. These sort of feelings can easily help to augment, or even commence, a Fi-Si loop. If Ne is always sabotaged, then the possiblity of ever being other than
sad/unhappy is nullified. I'm wondering if anyone has suggestions on how to avoid this train of thought?
I have in the past found it useful to consult TJs about such matters. They look at things quite objectively. ISTJs are quite good, since they can use tertiary Fi to engage with you. I've heard things like "Well, nothing can make you feel worse than how you feel right now. Give something new a go and see how you feel." Other NT suggestions like "You don't owe that person anything, so don't worry about him/her" or "You're being too hard on yourself. No-one is perfect." are also useful. ISFXs can also be quite good to talk to ("This must be very upsetting for you.").
I suppose, in this situation, INFPs need to be more like ENFPs, and allow the Ne to carry us through. We need to immerse ourselves in newness, whatever it might be, and then force Fi to operate post hoc. The key is recognising when we feel this way, and knowing how to deal with it. There also needs to be some way in which we can alleviate ourselves of the belief that we owe people to behave in a certain way, or that we are the guardians of everyone's emotions.