There could be several reasons. It might be that they don't want to be reminded of the past with you. Or perhaps they have new things going on in their life and aren't focused on your social media. Maybe they just don't use that platform much anymore.
It could be that they want to avoid any reminders of the past or are simply too busy with their own life to notice. Maybe they don't use the platform as often as you think.
There could be several reasons. Maybe they are trying to move on completely and don't want to be reminded of you. Or they might be respecting your privacy and the break - up by not interfering in your life through your stories. Another possibility is that they are simply not interested in what you have to share anymore.
It depends on how you feel about your ex still. If you're over them, then it really shouldn't bother you. But if you still have some feelings left, it might sting a bit. However, remember that they're an ex for a reason. Maybe they're trying to respect the boundaries of the break - up, and you should too. So, try not to let it get to you.
Maybe they're trying to move on completely. They might think that watching your snap stories will bring back old feelings or memories they don't want to deal with.
It's hard to say. They might be trying to be respectful of the break - up and think that watching your stories would be inappropriate. It doesn't always equal to not caring. Maybe they care so much that they are trying to move on in a healthy way and watching your stories would set them back.
It could be that he's not really interested in that kind of content or doesn't think it's relevant to him. Or perhaps he didn't even notice that you shared the stories.