I know when dealing with my ex the most frustrating thing for myself, a dom Ti, is her inconsistent lack of logic to get her way. She will use logical reasoning only to at a later point turn it around and do what she was against because all of a sudden her situation changed. So the logic used against me no longer applies. Her reasoning and logic is very goal driven as opposed to big picture driven. It almost like it's an attempt to control external logic. With certain types they are very good and it works, but dom Ti can see through it. The only thing is that I swear she believes this logic and not quite as manipulative as it sounds. Almost like a combination of F and T cause the logic to become what she believes. I don't know. Just a bit of what I see.
I am just speaking from my experience with ENFJ. She always said I was her voice of reason because she had to much of a fight or speak before thinking.
I am purely speaking through info only. No emotions or anything behind it. I am curious to see how it is from inside a dom Fe. I still have to deal with my ex because of my son and I am always looking for better ways to communicate because ours is very hit or miss. It's like tossing marbles into a field of land mines. Both ways, not just her blowing up. We just blow up in different ways.
I haven't read the whole thread yet but I want to answer this, from experience I find that as much communication as possible and needed is paramount with such opposites as ISTP and ENFJ. This is rule #1.
Then over time the land mine seems to clear up, as there will be more of a logical picture of why the things happen (this is from my own POV, I don't know the ENFJ POV). What I do is just tell them how I see the situation, via a very logical explanation and I make them talk to me too. Then, a lot of analysis from my part.... where I take into account the Fe as some sort of logical facts too. Otherwise this analysis wouldn't work! Over time less of that analysing is needed, of course. And then I discuss with them more and find a solution. But yes it's complicated sometimes
And yes, I experience the exact same about their inferior Ti as you describe. Yes it's like a bit of a mask of external logic, I liked that observation of yours. I assume that's due to things being coloured by extraversion.