Your girlfriend sounds a lot like my boyfriend's previous relationship. Ultimately there was nothing wrong - they were just two different people. He has mentioned some things (jealousy and insecurity) that sound like she was aware of a distance or them growing apart and started freaking out. I would wager your girlfriend is doing the same. At 6 years you're at the point where you "shit or get off the pot" and since you haven't shit, she's panicking you're going to get off the pot.

That said, you guys sound like two different people. My boyfriend mentioned how his ex was an introvert and he's an extrovert. He didn't realize until they'd broken up how much he had given up just to make her happy, and how much he was missing out on doing (basic stuff like going out with friends, playing in rec sports teams, etc.). It wasn't like she was controlling or told him he couldn't do those things, but her being an introvert and him wanting to make her happy made him more of a homebody, too. (We literally just talked about this last week so it's fresh on my mind lol)

It's okay for things not to work out because you're different people. In fact, it's best now to acknowledge those things before anymore time is wasted or commitments are made. Don't compare her to your friend's wife, though. That's not fair to her or you. It is okay to recognize that you are an extrovert who wants an extrovert.

I think you need to stop focusing on your friend's wife as a person, and start focusing on your relationship: what makes you and your girlfriend "good" together, and what qualities do you want in the partner you want to share your life with. If she doesn't fit into that, you guys need to both go your separate ways so you can find that person. There's nothing wrong with that.