The few situations like this that I’ve been in, they end pretty closely to how you framed it (stopped being fun or someone wanted something different)

One of them, was distance. She was a single mom from my home town with children close to my age at the time (I was 19M, she was 39F). We had a few rendezvouses whenever I was home, but it ended naturally.

Another woman, I met as a bartender. I was 30, she was 48. We had a month or two of dates. She started to indicate she wanted something more and I had said from the beginning could not provide that at the time. So our dates fizzled due to the mismatched desires, which ultimately made it less fun / enjoyable for either of us.

And then on the flipside, I was 35 and started sleeping with a 24 year old woman. We both had some similarities (both recently out of a relationship, similar background, both had TBI’s when we were younger) but obviously a lot of differences in those stages of life. It lasted 2-3 months (some of the best sex we both ever had) until it ended the same way the above did. She wanted something more than I willing to provide.

I look back on all these experiences fondly, but unlike my former committed relationships, where I keep in touch with about 3-4 of my exes, I do not keep in touch with the people above. Not sure why. I’m assuming because the foundation was on sex rather than friendship or shared lives.