((Sorry in advance, this got longer than I intended.))
Having had and lived with an ENTJ boyfriend for ten years, and also having a job in a place that has a disproportionate number of INFPs present, maybe I can help you figure it out.
I find on occasion that when there is an interpersonal/job-related problem at work that I am usually not even remotely aware of, that my INFP manager will actually spend the entire day working herself up to broaching the subject, and that when she does, it's in a very side-stepping kind of manner. In spending that entire day figuring out the best way to approach me about something, she actually behaves differently and anxiously, and I notice it right away. What generally ends up happening is that between her acting tense around me all day which makes me overthink what could possibly be up (she is fully an F and I am very strongly T), and then side-stepping into the subject as if it's something major that could get me into deep trouble, we are both a bit jangled by the time I realize it's a bandaid she could have ripped off first thing in the morning without me even blinking. It's frustrating, but I generally don't feel like stabbing her.
I am assuming that you approach this guy in a way that you intend to be subtle and non-threatening when something is up. Are you a superior? A coworker? Are you friends with this person, or just distant acquaintances? My boyfriend does not suffer fools, especially when they are superiors who are just "doing everything wrong". He will come home sometimes and just rant about it because the frustration gets so high. If he feels someone is an incompetent worker (or just incompetent in general), or doesn't particularly like them, or just doesn't know where they're coming from even if he does like them, they will be summarily dismissed and the event will definitely stick in his craw so to speak. I'm not calling you incompetent, but it's possible that he may question your ability compared to his own because you're coming from very different places in your decision making. As someone who does the same thing to a lesser extent, I've had to learn a long lesson that people who make their decisions from a strongly F standpoint can also be incredibly sharp, and not to flat out dismiss them.
As for just how angry he gets, my bf does get pretty angry when his capability is called into question, but he is definitely not a closed book when it comes to criticism either. And he's not violent. It's possible you do the same thing my manager does to some extent, and he unconsciously gets angered by it because it's not to the point and out of the way quickly. It's also possible that on top of things, he just flat out has anger problems. Knowing a few INFPs, I know that they do tend to feel a bit gobsmacked sometimes when someone in the room is out of sorts, whether or not it has anything at all to do with the INFP. The INFP will actually somehow take the blame for that discord onto themselves, it's kind of dismaying and fascinating to see really. It's quite possible that he does take some amount of offense to it and your infp mind always seeking for things to be okay "over-notices" the fact that he is not currently okay.
