...Whenever I meet someone, I always feel like we have a connection. Over a period of time, it becomes obvious that I missed judged the person and there is not much we have in common, or much I should have liked about them in the first place! I just can't help it, though. So...
Is it normal that I never learn?
Also, some advice on how to stop this irrational behavior would be nice, and very much appreciated...
Is it normal that I never learn?
Also, some advice on how to stop this irrational behavior would be nice, and very much appreciated...

Imagine society was entirely composed of clones of a single human being. Surely clones would completely understand each other, right? But think about it - even then, with a population littered by the same mentality, a clone in Chile might experience an earthquake that a clone in Germany would not. The Germany clone wouldn't understand the experience of the earthquake, so the two clones are informed by discrete experiences and must ultimately be different people.
Even two clones can only view the same apple from different angles. So a society without any misinterpretations would have to be a society populated by people who share the exact same mentality AND the exact same experience, i.e. ONE person (see Leibniz's Identity of Indiscernibles). Only an hollow universe containing a single lonely being would be free of misinterpretations.
We're left to fill in the blank spots that we can't know about a person. Which means that ultimately, everybody you know is a personal projection, at least to some extent. So I wouldn't get too hung up on whether or not you're completely right. Because you never will be. The only thing you can do is stop guessing, and be content with getting what they give you.
Something I think would help me as well; is if I didn't always trust people so much when I meet them. I can't tell you how many times I've put a decent amount of trust in people I know nothing about. It is exciting to meet people and learn about who they are, but I need to think more before I put so much into a person.
I always thought that by trusting people I would be building a strong relationship with them. Then, I see they are very undesirable and (sorry for what I am about to say next) very disgusting. Then I feel violated in a sense and at the same time I start to dislike myself for not learning, ever.
It is a tough mold to break...
To make this more clear to anyone else; I am not talking about falling in love with these people. Just friendship and thinking that we are alike in someways.
Appreciate the positive feelings you have for a new friend but take a step back and let the friendship/relationship go at its own pace, it might make all the difference, rather than you being 'full on'.