Perhaps she doesn't know what to say in response. Watching your stories is her way of staying updated on your life without having to come up with a reply. It could also be that she doesn't want to engage in a conversation directly but still wants to be part of your world through your stories.
Send her a friendly and non - pushy message like 'I noticed you've been watching my stories. I hope you're having a great day!' This shows that you're aware of her viewing but also keeps it light.
Maybe he's shy. He might be interested in you but doesn't know how to start a conversation. Just watching your stories is his way of staying updated on your life without having to interact directly yet.
I don't think you should be overly concerned. Everyone has different ways of interacting on social media. Some people are more passive. He might be one of those. He could be enjoying your stories at his own pace without feeling the pressure to reply immediately. If it really bothers you, you could try sending him a friendly and non - pushy message to see if he'll start a conversation.
Perhaps she just prefers to observe silently. She might be the type who likes to take in information passively, like through your stories, without the pressure of having to reply to a text. It could also be that she's in a situation where she can't text back at the moment, but has time to quickly check out your stories.
It depends on your relationship with her. If you're just getting to know each other, it could be normal. But if she used to text back and now doesn't, it might be a sign that something has changed. However, just the fact that she watches your stories shows she still has some level of interest. So don't worry too much right away.
It could mean she's still interested in you but is shy or doesn't know how to start a conversation. Maybe she enjoys getting updates from your stories without the pressure of direct interaction.
It could mean she's just casually interested in your content. Maybe she doesn't want to commit to following you but still enjoys seeing what you post from time to time.
I don't think you should be overly concerned. It could be that she's just exploring different people's stories and yours caught her eye. There's no real indication that there's anything negative going on just from her not following but watching your story. In fact, she might eventually decide to follow you if she continues to be interested in your stories over time.