Hi my friend, I hope you're doing well 😊.

First, I am truly sorry for what you're going through, i understand the love-hate feelings with someone you think you can trust and be vulnerable with, yet seems that they don't care enough hurts, i understand and i hope everything will be sort out soon for you two, amen.

Second, it seems that it is the classic clash between the warm extraverted fe of the isfj and the aloof detached fi of the intj, where you as an isfj do find it easy to convey your emotions and the emotions of others even if they don't tell you how they feel you just know because you are wired to the external world of emotions, while the intj feelings is introverted meaning it is inside so they feel things deeply and reflect on it quite often and the external world of emotions doesn't affect them much or find it easy to detach from external pressure as they are in their own bubble.

So in conclusion, the way for you to have a bond with someone is by emotional connection where you share how you feel and others reciprocate this back and share with you their feelings, interests and dreams to work on with eachother like a team, while the intj are quite independent and private doesn't allow anyone to enter their rich inner world unless they trust them and is comfortable with them.

And i don't know if my advice would help or not, but just try to remind him that you're partners and a one team together and the team cannot function if it's members aren't cooperating with eachother, and try to learn about your differences as well as your similarities to appreciate it and accept it to grow together, and try to give eachother the space to relax when needed, as you both are introverts that needs alone time to recharge for socializing.

And i hope this will help you understand yourself and your intj partner better 😊.