However, my relationship with my INTJ boyfriend is absolutely wonderful. This is partly because of things related to our types, but a lot of it has to do with the fact that we have a lot of core beliefs and opinions in common, so when we argue, it's usually not about things that are close to our hearts. Of course, that happens, but when it does, we make sure to stay calm, understand each other, and speak carefully to avoid giving offense.
Arguing is a central part of our relationship. It is how we amuse ourselves, how we learn and understand, and how we resolve issues. We think that disagreeing is fine in many situations, and our primary aim is to ensure that our side is understood and accepted. We might become irritated with each other, but it doesn't affect us outside that argument.
We complement each other. He is calm, cold, and deliberate. He steadies me and keeps my head out of the clouds when I need to be realistic. And I keep him from brooding and forgetting that there are things to be happy about. I offer points of view that he has not considered, or dismissed too quickly, and sometimes, I can present them in such a way that he is forced to acknowledge their validity.
We challenge each other, as well. It's like the "unstoppable force meets immovable object" thing. For both of us, but mostly me, an argument is a challenge, and a challenge is a game. He likes to prove himself, and I like to play games.
The nonadventurous aspect of him is easily my biggest fear for our relationship. We want most of the same things out of life, with one exception. I want to explore. He wants to stay within a familiar environment where he knows his capabilities. I don't beleive I'll ever get bored of him, but I might get bored of adventuring seldom, and alone, while he worries about me.
But...communication. We might neve find a solution to that problem, but we can be sure it won't be a thing that festers.
In short, I think an ENTP and INTJ can have a beautiful relationship, if they want the same things, and they are committed to constant, honest communication, so as to avoid misunderstandings. If they can't do that...well, I would expect much in the way of fire and explosions. I could certainly see that happening with us if one of us refused to listen to the other. Scary.