#1 thing your INFJ would like you to know, but can't find the courage or the words to express
Your perception of me can make me hate myself. Here's why you have that power:
1. Because we lead with an information gathering process rather than a decision making process, we are not married to our perception about life, the world, or ourselves.
2. We are easily influenced by people whom we love, or who treat us in a way that meets our needs.
3. We are "outer harmony people", meaning that we are wired to create harmony in our outer world and as such our conditioning is to self sacrifice, rather than "selfishly" ask for our own needs to be met.
So, if you are an important and an influential part of our lives and you, for whatever reason, are having ill feelings toward us, we can easily perspective shift into hating ourselves too.
The biggest issue is not the trigger from you, it's that once we are on the "hate wagon", we go into our introverted loop of Perspectives (introverted intuition) and the tertiary (10yo inner child) Accuracy. At this stage, do we not only understand the reasons of why you are unhappy about us, but we also start looking for additional evidence of why we are unworthy of love, and why we should continue hate ourselves alongside you.
We remember how we let you down. We count the ways we disappointed you. We dig out all our old in-competencies and failures and go for the throat. But here's the thing. It's not your throat. It's our own.
This eventually leads to feelings of hopelessness and "what's the point". At this point the INFJ feels like there's no other way out than to either close the door on the relationship, or, the more common way of dealing with these issues; indulge in a substance, be it addiction-grade intimacy or any other kind of inferior process (3yo inner child) activity that is to do with immediate sensory gratification.

Here's the thing: you're not responsible for our happiness or our emotions.
Sure, sometimes we fuck up, and yes, we have to own that and make it right again.
Having said that, we would like to ask you take responsibility for your feelings and be aware of those times that you might be taking your personal pain out on us.
The thing is, that long after your ill feelings toward us have passed, we are still battling with forgiving ourselves for not being perfect. Please know that you are living with a very impressionable person.
If you can own your feelings, and if we can own our imperfection, then we both can begin to take responsibility for the energy we bring into the common space of our relationship.
We, as INFJs, need to learn how to self parent with the Harmony (extroverted feeling) process, instead of falling into that introverted loop. The harmony process is all about us bringing our own needs to the table and insisting that they are important. While we learn, how you can help us is by encouraging us and reminding us that we are lovable, even if we are not perfect. This will directly strengthen out inner parent Harmony process.
If you love and encourage your INFJ, he or she will always be yours.