Ending a casual connection...

I unexpectedly matched with a guy I had a crush on from the gym for months without realizing. Clearly when he came up to me and I realized it was him I was super excited. We would have the funniest time and conversation. We'd flirt a lot and only once spent private time at my place. The conversation was also super nice and we were still very relaxed and enjoying each other when we bumped into each other at the gym. This went on for only a couple of months.

Recently he would even start working out next to me when we were there. I liked the attention.

The problem was, of course, he was interested in a casual situation and so was I when it started. But in the last few days I started discovering that I'm entering a part of my life where I want to fearlessly admit to myself that I am opening up to a bigger connection with someone. Since we had initiated as a casual connection I didn't think it was fair to him or myself to apply new expectations to our connection and or him when we had previously communicated we were just casual, so today i texted him and shared that my perspective with myself is changing and that we should just stay as platonic friends.

But I can't get this feeling off my chest that I ended something fun, and I am feeding ideas that maybe he would come around now. I'm in a way looking for reassurance that I didn't prematurely interrupt something that was blossoming, or maybe my daydreaming and new desires are just incorrectly being dropped on him because he was there. But even so, if he was interested he would tell me and I didn't completely take that option away by walking away.

The hindsight anxiety is stressful. But in the moment I was certain it was the best thing to do. Help.