I'm an ENFP female engaged to an INTJ male; and true to my type, I tried to go through the other answers first but got too excited about answering myself so here I am
The relationship I have with my INTJ has been hard earned and maintained for almost ten years now; in the beginning I felt compelled to push to the core of him because I sensed something deeper that I recognized and had been searching for. It was not easy; my INTJ wanted to keep things on the surface for a long time, and tried to prevent me from seeing him as who he really was. But I am nothing if not tenacious; and ENFP will tell you when they have set their hearts on something nothing will deter them. So for four years I chipped away at that wall; a unique aspect I have come to appreciate between our types is that the INTJ doesn't ever have to give much for the ENFP to see the full picture and understand them. So gradually over four years I developed a true picture of this man, and diligently showed him love until he realized he could trust it. Now I will say that a LOT of our early dynamic was a result of us being very young and going through the steps to maturing as individuals as well as within our types.
Although the dynamic is tricky to navigate in the beginning and does require constant attention and upkeep, the rewards are beyond worth the effort. We have lived together four years now, and our relationship and understanding of each other has deepened so much. He does truly get the chaos that is my mind, and he is the best at calming me and keeping me on a steady course. He motivates me to keep pushing in life. Something I can say that I haven't seen a lot of ENFPs answer with though is how WE improve the INTJs life. My fiancé had told me repeatedly that I am the only reason he had been able to develop emotional maturity; I keep his mind and heart open, I keep him mindful of the emotional side to situations, I make him want to be more compassionate and caring. And it means a great deal to him. Because of me in his life he learned to focus on patterns instead of rigid plans, and he now tries to understand people beyond the surface of what they say.
I saw it mentioned earlier, but a lot depends on the ENFP and INTJ being mature and willing to accept flaws in themselves and desire to work on them. It took us almost five years before we could really be together, because we both had to learn some life lessons otherwise our relationship would have exploded quickly.
As to the INTJ seeing the ENFP as "too emotional" yes it is very easy for them to see us that way. But when the INTJ cares about the ENFP it becomes less about us being too emotional, and more about them wanting to understand why we feel so strongly. We are an endless puzzle to the INTJ and that's just part of the magic!