How can I let go of a relationship that ended long before it even began?
We've known each other for a long time; he was my elementary school classmate. Later, we went our separate ways, but in high school, we became classmates again. He loved me a lot at that time, but I didn't feel the same way, so we never got together. As we grew older, I got married, but I often dream about him and feel regret that we never ended up together.
Sounds like you're dissatisfied with your current marriage. I'd look at addressing that problem first.
Look up 'limerance.' There are many online resources, including a few good subreddits. You may not have it, or may not have it strongly, or it may come and go — but some people are highly affected by having limerant obsessive feelings for someone, sometimes for decades. Understanding how it works may help you move on.
This may sound crazy, but play it out? Write it down, type it out, or even get a private roleplaying LLM to chat it out with you.
Typing out or roleplaying very private past regrets (and not relationships in particular) has been quite therapeutic for me. Its kinda what got me into LLMs, as they are like a extension of your brain to bounce ideas off of.
Why let go? Unless it’s harming you or jeopardising your relationship. Treat it as a happy dream you can take your mind into, once it’s a happy dream you can control the ending to your like. Your mind will forget when ready and that’s often out of control.
I can't relate but, i guess try to remember why you didn't like him at the time? We tend to engage in nostalgia and see the past with rose-tinted glasses...