It depends on the platform. Some platforms offer this functionality. They might show you a list of who is currently viewing your private story and if someone leaves, that change will be reflected in the list. However, not all platforms are the same. Some may not provide any indication at all that someone has left your private story.
You could tell if someone leaves your private story when you don't get any feedback or response from them that you typically did before. Maybe they don't mention it or show any interest when you bring it up. Sometimes, it's just a gut feeling based on the change in their behavior towards you related to the story.
Most social media platforms that have private story features don't offer a built - in way to see who has left your private story. This is because privacy is a key aspect of private stories. They are meant for you to share with a select group, and the focus is more on who you include rather than who leaves. For example, on Snapchat, there's no clear indication when someone exits your private story viewership.
When you make your story private, it's designed to be exclusive to you. Generally, no one else can access it. But always make sure you're using a trusted platform and have your privacy settings configured correctly for maximum protection.
If you make your story private, the general rule is that no one else can view it. It's designed to protect your personal sharing. But keep in mind that technology isn't always perfect, and sometimes there might be unexpected issues with the privacy functionality.