Well, first of all, don't take it too personally. Maybe he's just going through something in his own life. You could try reaching out once in a friendly way to see if there's an issue. But if he doesn't respond, just move on. There are plenty of other people out there who would be interested in your stories.
It's possible that he lost interest in the content of your stories. If your stories have been about the same thing over and over, he might have gotten bored. Another reason could be that he has found other sources of entertainment or information that he prefers.
Perhaps there was something in one of your stories that made him/her uncomfortable. It could be a topic, an opinion or even just the way you presented it. So he/she decided to stop watching.
It's possible that he lost interest. Maybe your stories have become a bit monotonous or not as engaging as before. For example, if you always post the same type of content, he might get bored.
Personally, I would consider confronting him if it's really bothering you. However, be prepared for different outcomes. He might be honest and tell you why he ghosted but still watches your stories, or he could just get defensive. If you're strong enough to handle any response, go for it. But if you're still a bit fragile from the ghosting, it might be better to let it be for now.
It could also be that something in the story made him uncomfortable. For example, if the story contained topics that he didn't like or disagreed with, he would choose to stop watching it. Also, perhaps he accidentally clicked away and then just forgot to come back to it. There are many possible reasons for this situation.