It could mean they're not ready to respond to your message but still interested in your life. Maybe they don't know what to say or are in a situation where they can't reply at the moment but still like to keep up with what you're doing through your stories.
You could just ignore it. Don't let it bother you too much. Maybe they'll come around and reply later. If you keep being cool about it, it might put less pressure on them and they might be more likely to start a conversation eventually.
She might be a bit conflicted. She enjoys seeing your stories, which shows she's curious about your life, but leaving you on read could be because she's unsure about her feelings towards you or how to respond to your message. For example, she could be afraid of leading you on or getting too involved at the moment.
There's a chance they blocked you in a moment of anger or impulse. And now, they can't resist seeing your stories because they still care about you, at least on some level. They might be too proud to unblock you directly but still want to keep an eye on you.
Maybe he's conflicted or unsure about his feelings for you. Watching your stories could be a way to keep an eye on you without committing to communication.
Well, it could be a good indication that he likes you. Watching your stories shows he's paying attention and might be interested in what you're sharing. However, it's not a definite sign on its own. Maybe he just enjoys the content or is a friendly follower.