It could mean that they're not ready to reply yet but are still interested in what you're up to. Maybe they don't know how to respond at the moment or they want to take their time thinking about what to say.
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.
It's hard to say for sure. A story might seem true but could have elements of fiction mixed in. You'd need to do some research or look for reliable sources to verify its truthfulness.
They might be busy. Just because they watch your story doesn't mean they have time to type out a reply. They could be multitasking and quickly glanced at your story while in the middle of something else.
There are several possibilities. One is that they are simply forgetful. After watching your story, something else distracted them and they forgot to reply to your message. Another reason could be that they have a passive - aggressive attitude. They want to show that they are aware of your existence (by watching the story) but are not in a hurry to communicate with you. It could also be that they are in a complex emotional state. For example, they might be interested in you but at the same time are hesitant to start a conversation for fear of saying the wrong thing or getting too involved.
It could mean they're still curious about your life but don't want to directly engage. Maybe they miss you a bit but are trying to move on and think ignoring you is the best way while still being a bit nosy about what you're up to.