I read that when a girl is sitting next to you, if she has her legs crossed towards you (if I am on her left, her right leg should be over her left) then that means she is open to the guy. If it's the other way around, and she may even have her arms crossed. That could mean she is closed towards you.

Sooo, with my girlfriend, who I've been with for 3 years, and where everything is fine if I'm honest, how come her body language is always closed. No matter what side I am sitting on, her legs are always in the "closed position". This sounds so sad to mention but I honestly don't get it. I seriously don't. I've really tried to think why. I just don't get it, because everything is as fine as it could be in our relationship. It's just a minor thing that is bugging me a bit. Any thoughts on this people? I don't wanna say body language is bullshit because I feel I'm not facing the problem. Her body language is going against the books and it's bugging me.

Lol you gave me a good laugh. Your reading too much. Take a break, sit in a park and observe everyone's body language (just dont be a creep about it) even pay attention to your own body language

Body language is triggered by our nervous system. You have to look for clusters. One movement isnt enough to tell you what is going on.

I always tell me students to question the person's motive. Is the person nervous, excited, calm & relaxed? What are the logistics? What is the topic of convo?

So for your girl, it can be just that she is comfortable sitting that way. Only how to know the truth is pay attention to the rest of her body when she crosses her legs. Pay attention to the timing & logistics. Crossing legs doesn't necessarily have to do with attraction. It can also have to do with comfort