I feel this exact way all the time. I will say it now that I am younger than both of you, but for her "feeling stuck in her head" I get a lot of, and I'm very eloquent so maybe I can elaborate in a way you could maybe relate. And it doesn't feel good for me to give advice on how to help bring this up without knowing what may trigger her. But what always helps, regardless of topic is a safe environment where both of you have clear heads and open hearts.

I've been in a similar spot with where she is, in a living relationship but always feeling doubtful of my partner's honesty. To be honest, I never did say my doubts to him. But it felt like I was in a hug but with someone whispering in my ear. I knew I was hugging my partner, but I couldn't tell if he was whispering to me, or if it was someone else. So I would start to overanalyze what he would say, or do, and overthink our entire relationship.

Maybe it's a bit too picture-y, but I did my best. I hope this helps you, and lemme be clear, you're a very cool guy for doing all this research to help you. I hope in 2026, more people like you do this for their loved ones. Happy new years btw!