How did I know? Because everyone else I dated, I'd be talking to, and suddenly I'd realize that I had no idea what planet her brain was on. I just couldn't understand where she was coming from, at all. With my wife, sometimes she'd have to explain, but the explanation always showed that she was coming from somewhere I could understand.
Also, as we got closer to each other, I never hit a wall. There was never a line inside her mind or heart that I wasn't allowed to cross, to see what was behind it. She never kept a private version of her that I was excluded from. (I'm not talking physically here, I'm talking about her mind and her heart.)
> Half of me thinks that you have to work hard and be diligent to make it work, and the other half thinks it's just a matter of good interaction between your natural selves.
It's kind of both.
It better be "good interaction between your natural selves". Do you want it to be hard work? For the next 50 years? It has to be OK for you to be your natural self. You can't maintain anything else for the long term.
And yet, you do have to work at it. If you put zero effort into it, well... if you pay for nothing, nothing is what you're going to get. I found in my own marriage that, every year to year and a half, we realized that we weren't as close as we used to be, and we made a deliberate effort to rebuild. But feeling like we're still in the honeymoon phase after 20 years was worth it, definitely.