Well, there could be several reasons. Maybe he enjoys the content you share, or he considers you a close friend and wants to be updated on what's going on in your life. Another possibility is that he's just being nosy!
It could be that he finds your updates engaging or maybe he has a crush on you and wants to stay connected through your stories. Or perhaps he just has a habit of following people's stories without a specific reason.
Maybe he's just curious about your life or finds it interesting.
It could be that they haven't fully moved on and are keeping tabs on you. Or perhaps it's just a habit they haven't broken. Maybe they still care about you on some level and this is their way of staying connected, even if it's in a passive way.
Maybe he's just interested or curious about what you have to share.
He might be your biggest fan. He wants to be in the loop about everything you do. So, he checks your story as soon as it's available.
Maybe he just happens to be online and paying attention when you post it.
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.
It could be that the content of your story doesn't interest him anymore. Maybe the topic or style changed and it no longer appeals to him.
Maybe he's just busy and hasn't had the time. Or perhaps he's not interested in that kind of content.
Maybe he's just interested in what you have to share.
Maybe he's just lurking and not in the mood to text. Or perhaps he's too shy to start a conversation.