You could choose to ignore it. Just act like you don't care that they're watching. Maybe they'll eventually get bored if you don't give them any reaction.
You could just ignore it. If they're not making an effort to communicate but are still snooping on your stories, don't give them the satisfaction of a reaction.
Another option is to send her a private message, but keep it casual. For instance, you could say something like 'Hey, noticed you checked out my story. How have you been?' This way, you're opening the door for communication without putting too much pressure on her.
You could choose to ignore it. Just carry on with your life as if you don't notice. They made the choice to ghost you, so you don't owe them any special reaction.
You could simply ignore it. Don't give him the satisfaction of knowing it affects you. Act like you don't even notice he's watching.
You could just ignore it. If they're not making an effort to reach out, there's no need for you to overthink it. Just continue living your life and posting your stories as you like.
You could ignore it. Just act as if you don't notice they're watching. Don't let it affect you and continue with your life.
Another option is to block them. If their behavior makes you uncomfortable or you feel it's a bit of a mind - game, blocking them can give you a sense of control and closure. You don't need to tolerate this kind of confusing behavior.
If it makes you uncomfortable, you can block them from seeing your stories. It's your social media and you have the right to control who views your content.
You could react by simply ignoring it if you don't want to encourage any further interaction.
If you're curious about 'ghoster', you might try to drop some hints in your next stories to see if they'll interact more. For instance, you could ask a question related to your story content and see if they respond. But don't push too hard, as they might be someone who prefers to stay in the background.