Yes, if we decide that we want to let you in, then as long as you don't betray our loyalty, you have a friend/lover for life. The public INTJ may appear silent, judgemental amd sarcastic, but the private one, that few people see can be very different.
I've noticed this. He's funny and playful and nice with me, but in public he's extremely quiet, almost to the point of being awkward. He doesn't really come across as sarcastic, but he could definitely come off as judgmental and silent to those who don't know him well.
From my personal experiences, the intimacy factor between INFJ and INTJ is quite ferocious and deviant. Inferior Se definitely influences a hedonistic and animalistic dynamic. The thing that I found lacking in the relationship was the emotional support, especially when I was having emotional ups and downs. INTJs focus on solving problems, whereas INFJs focus on tending to their partner's heart. In discussions, INTJs often get involved in debates, so otherwise peaceful INFJs that seek consensus might not feel 100% comfortable in this situation. Sometimes I would have heated arguments about caring for people involved in a situation, as well as showing support for theories for theory sake. INTJs will dismantle this, even if they are romantically involved with you. So be prepared to have your values challenged. It may rile you up a bit. Compromise is seldom in their vocabulary. :P
INTJs are very very selective as to who they show their affections to. They can be sweet when they really care about you. But it isn't soft and squishy warm Fe love, though. INTJ Fi based affection feels different to me than Fe. The affections will be focused on you and your INTJ partner, with very little regard to anyone else. INTJs focus on you and them in the relationship, rather than taking in the rest of the family and friends. Fe looks to harmonize and get everyone to get along, whereas INTJ Fi is perfectly okay being alone in their personal pursuits. If you're looking for someone who will help you to deviate from being bound to pleasing others, which can be an issue with us INFJs and the infamous martyr complex, then an INTJ would help you develop even more individualism. But if you're searching for consensus, then an INTJ would challenge that. Potential issue with regards to aux Fe vs. tert. Fi dynamic.
But, even with these challenges, the connection with INTJs are rewarding. Getting involved in Ni-based meta discussions can be liberating. INTJs are helpful in pointing out steps to realize your goals. There may be factors irl that you as an INFJ may have missed out. INTJs come up with strategies to get there. Be prepared for them to bluntly tell you if something will not work, though. Even when they love you, they will still offer constructive criticism. But the meta-discussions are well worth it. It usually helps when you two have a common passion to build off of.
There's overall a good dynamic, but be prepared for bluntness.
This is lovely. My ENFJ is rather low on the extroversion and this description is very similar to our relationship.
I like to rock n' roll all night and *part* of every day. I usually have errands... I can only rock from like 1-3.
I'm an INTJ, and my wife is an INFJ... we are a same-sex couple, so who knows if that changes things (?). Like others have been saying, I am more of my goofy self when I'm with her, where elsewhere I'm definitely more quiet and reserved. When we first met, we clicked in an amazing way. I felt like she 'got' me, despite what I considered my odd-ness. She was patient with the fact that I was so quiet and private at first. And she had a way with people that I really admired. She stood up for people, and was incredibly smart.
There's a lot that works for us. But I've found that having some extroverted friends is helpful, so we don't end up holed up somewhere. When you have two introverted, inward focused people, it can get a little intense. Sometimes good, sometimes bad. Communication is the other thing. When she wants me to understand what she's feeling, well, that's not always easy. And we end up talking past each other. But I think I would have that problem with most people. I rarely ask a lot from her. Not outright anyways. I never really liked "needing" things from others I guess, even from her. So because of that, I have to try harder to make sure I'm not forgetting her. Again, probably would be something I'd need to work on with anyone, not just an INFJ.
Anyways, that's just some of my experience.