What do you mean by not understood?
Is there a way your friends can help try and relate to you better? Would you be ok with them just coming out and asking questions about you to help them understand you?
A lot of it is about how we think abstractly/in code, as Fuzzcrossed mentioned. I have to completely tone it down and translate it for my INFP. She simply cannot keep up. She'll relate to what i am saying, but she can't feel the effects the way that i do or provide much more than a listening ear.
It's hard to feel understood when you've got to sift through your own code and may just get a glazed over stare back. It happens frequently.
I've found that my INTJ internalizes a lot and truly views feeling as a weakness. If we ever attempt to relate it falls short because she won't let herself get to where i am and she can't empathize with things that she hasn't experienced. I'm easily misconstrued by her for that.
To combine something Fuzzcrossed and nynesneg said, it can feel like ENFJs have compartments. Everything about us and how we are perceived is how we truly are, but the deeper compartments are stationary and less likely to change. The outer compartments are malleable and how we adapt to different scenarios and people. We are never being fake, but to try to pin-point us and understand us without viewing the deeper compartments won't happen easily/properly.
There is a certain understanding that i've only found with other ENFx people. I get feedback that i can see genuinely relating and then experiences or advice beyond that. It's as though we don't just hear each other, we listen and attempt to guide one another on a more real, deeper level.
It's very important for people to be more than just surface level with ENFJs. We can have heaps of friendships and have discussions left and right, yet if we don't feel that depth then there's a void.