Why is my ex unfriending me on snap but watching my story on FB?

For about a year my ex was viewing my snap stories everyday, here and there messaging me and was/is in a relationship. I respect that, so there wasn’t much communication. Couple months ago he unfriended me on Snap, ok cool. Yesterday I posted to my FB story and he viewed it. I go by a nickname on there, but my picture is the same and he would’ve recognized it. Figured maybe he didn’t remember we were added on FB or didn’t know my nickname on there, today were still friends on FB. Maybe mine played on accident, but it’s just so confusing. Like why keep me on FB but not on Snap, why still be defensive of me when he’s in a relationship? Its been years since we’ve been together

I had another ex years try and re-add and follow me on all my platforms for a booty call. I turned it down, we’re still friends on those platforms, but he never views any of my stuff.