Well, without more context, it's hard to say exactly who 'he' is. He could be a friend, a family member, or someone who just happens to be very interested in your stories. Maybe it's your best friend who always checks your updates first.
Perhaps he has a special connection with you. Maybe he's your close friend, a secret admirer, or someone who just really values what you have to say. Being the first to watch your story shows that he gives your content priority over others he could be following.
It could also be someone who has a secret crush on you. They are so interested in you that they make sure to be the first to see any new stories you share, hoping to get a glimpse into your world and feel closer to you.
It might also be that he is just a very active social media user and he has his notifications set up in a way that he sees your stories right away. However, the fact that it's always your story that he's first to view does make it seem like there's a special interest there. It could be that he values your friendship a great deal and doesn't want to miss out on any part of your life that you share through your stories.