Hi, I am an INTJ. I think it is really a difference between Fe and Fi, and having Fi in a rather guarded position, for an INTJ, that being the third slot in our cognitive function stack.

I believe that the way in which each other understands being emotional is, in a way, a bit different.

As Fi users, with Fi tert, we do still value our emotional world quite a lot (and usually types tend to value their third function, even if they do not have as much control over it). We do have strong emotions and opinions, but, however, we tend to be afraid to express that to the outside world (usually because we have not yet found and understood the “reason” why we feel in a certain way. Unless we can explain it through some Te build framework we may seem confused about how we feel like, even if we do feel something strongly), and, most of the time we may not even know how to do express them, even after we fully embraced the emotions we feel and understood their cause.

Moreover, INTJs are rather avoidant of reciprocating (especially strong) immediate emotions others display like sudden excitment, or joy, or extreme sadness, because we need a lot of time to fully embody an emotional state, and only after we ruminate over it and we are fully sure that that is the way we feel, can we reciprocate.

As I understand Fe, I think (and now I am hypothising based on what I read so sorry if wrong) that you generally can read the “emotional atmosphere” of people around you, and find it naturally to reciprocate, without the need to have filtered the perceived emotions of others through your internal dataset of emotions and realise if that feels fully relatable to yourself firstly. We, INTJs, sadly, are blind to that. Fe is our blind spot, so we cannot really do that. The atmosphere of someone’s feels and the natural way of harmonising with them by reciprocating is like a power unkown to us. We cannot see it. We can try to mimic what we see you do, but it feels strange and awkward for us because we need to always relate emotions through our internal framework, to us, firstly.

I think that the best thing to do, would be to ask your INTJ to express his feelings more frequently, even if they are unsure yet if their feelings are correct, and listen to them trying to work out their feelings (through a more or less Te manner), assuring them that you understand that they may not be exactly how they feel like and make sure not to judge them based on what they say